bluuebunny/crossref_metadata_2025 huggingface dataset:
Thread Reinforcement of Screw Connections in Lightweight Design
Authors: Hoernig T. , Friedrich C.
Published: March 2015

Design engineers today desire to develop more lighter and compact components with higher performance capabilities against the background of saving resources. For this purpose, low strength and lightweight metals such Aluminum or Magnesium are preferred on one hand. On the other hand there is an increase in load requirements which needs higher clamp force between these components. In such applications length of thread engagement requires special focus. At the same time from industry perspective it is essential to have effective dimensioning methods to develop new products in shorter time and at a reasonable cost (economics).

Besides the increase in length of thread engagement, the tribology of mechanical contacts (i.e. increased friction coefficients and limited loading capacity due to higher contact pressure) plays an important role in the tightening process. The result is that the desired preload is often not achieved with a standardized tightening specification (reasons: high friction decreases preload for same tightening torque by high torsional stresses). In this contribution experimental results of tightening screws with nut components made from aluminum alloys are analyzed for their frictional behavior by using a multi-channel screw assembly test stand. Risks and dangers associated with tightening process are highlighted and suggestions are made for improvement in thread reinforcement.

An established method to realize thread reinforcement is using wired thread inserts. For these elements several standards concerning geometry and strength exist but no dimensioning method is available. These thread inserts themselves have a higher strength than the nut thread material and transmit the preload force of the screw with a greater surface area than the original nut component. This leads theoretically to an increase in the load capacity of the nut thread. The approach of existing dimensioning methods by established rules and regulations for the design of bolted connections, e.g. VDI 2230, are not able to predict the behavior of reinforced thread engagements. Hence, an extension for the dimensioning of threaded engagement is essential for modern requirements. Experiments of tightening screw joints with wired thread inserts and with normal thread engagement are comparatively analyzed along with numerical calculations using Finite Element Analysis (FEA).

Conclusions are drawn from experimental and FEA results with the perspective of formulating an extended dimensioning method for thread reinforcement of screw connections in lightweight design. These points are interesting for every design engineer, especially in the field of lightweight design.
Ultrasonic Fluxless Soldering of Eutectic SnPb and SnAgCu Alloys: A Feasibility Study
Authors: Shi Jing , Wang Yachao
Published: March 2015

Compared with the traditional eutectic SnPb soldering, lead-free soldering has been a focal point for electronics packaging research in order for the industry to meet the regulations on environment protection. By eliminating the lead element from soldering process, the concerns on environmental pollution can be significantly reduced. However, the current lead-free soldering processes usually still require the flux chemicals for promoting wetting. The use of flux chemicals is not environmentally friendly. In this study, motivated by the potential benefits of soldering using ultrasonic energy, we carry out a feasibility study of ultrasonic fluxless soldering experiments on both the regular eutectic SnPb soldering alloy, Sn63Pb37 and the popular SnAgCu alloy, SAC305. By developing the appropriate testing conditions, the solder joints are successfully formed using the dipping ultrasonic soldering method regardless if chemical flux is applied. The effects of soldering time, temperature, and ultrasonic power are investigated. The results from SEM observation and EDS element analysis indicate that the use of chemical flux produces thicker intermetallic compound (IMC) layers for Sn63Pb37 alloy, and a longer soldering time leads to thicker IME layers for both solder alloys. However, a higher soldering temperature may not be beneficial to the growth of IME layer in ultrasonic soldering of SAC305 alloy. However, the driving mechanisms behind the phenomena remain to be investigated in the future.
Identification and Validation of Marusich’s Constitutive Law for Finite Element Modeling of High Speed Machining
Authors: Jomaa Walid , Daoud Monzer , Songmene Victor , Bocher Philippe , Châtelain Jean-François
Published: March 2015

This study aims to identify the coefficients of Marusich’s constitutive equation (MCE) for the aluminum AA7075-T651. Material constants were identified inversely form orthogonal machining tests and from dynamic tests. The proposed material model was successfully implemented in a finite element model (FEM) to simulate the high speed machining of the aluminum AA7075-T6. Deform 2D® software was used. A reasonable agreement between predictions and experiments was obtained. The comparison was based on cutting forces, chip morphology, and tool/chip contact length.
In-Silico Evaluation of Effects of Swirl Direction and Intensity on Aortic Flow Patterns Induced by an Aortic Pump Using Computational Fluid Dynamics
Authors: Albal Priti G. , Menon Prahlad G.
Published: March 2015

Congestive heart failure has reached epidemic proportions in developed countries afflicting an estimated 23 million patients worldwide and more than 5.7 million patients suffering from it annually in USA. Left ventricular assist devices (LVADs) have gained acceptance for non-transplant NYHA Class III & IV HF patients to provide full or partial circulatory support as a bridge to transplant or destination therapy. Recently, investigators have suggested advantages of deploying a continuous flow pump within the aorta, through transcatheter deployment (eg: Abiomed Impella pump) and an anchoring device to lodge the pump across the diameter of the ascending aorta (AAo). In this study we evaluate feasibility of such a device anchored virtually at the AAo of a patient-specific aortic arch, using computational fluid dynamics (CFD). Constant inflow rate conditions of 0.7 m/s in the axial direction with varying swirl / tangential intensity at the AAo inlet (viz. pump outlet) was modeled simulative of a range of conditions affecting aortic helical grade (viz. secondary flow), using FLUENT 14.5 (ANSYS Inc.). A change of swirl intensity from +30% (right-handed, physiological) to −30% (left-handed) swirl led to increases in peak WSS (by 10.31%) and mean WSS (by 13.04%). This simulation based pilot study indicates that WSS in transverse aortic arch is a versatile indicator of non-physiological helical flow grade and may be a promising design parameter for hemodynamics-informed aortic pump design.
Optimal Design and Aerodynamic Study of Leaned Transonic Axial Flow Fan Rotors
Authors: Razavi Seyed Reza , Boroomand Masoud
Published: March 2015

Multi-Objective Optimization Problems (MOP) are very usual and complicated subjects in Turbomachinery and there are several methodologies for optimizing these problems. Genetic Algorithm (GA) and Artificial Neural Network (ANN) are the most popular ones to solve MOP. In this study, optimization was done for leaned rotor blades to achieve maximum performance parameters including specifically stage pressure ratio, efficiency and operating range.

By bending an existing transonic rotor which is well-known as NASA rotor-67 in tangential direction, effect of leaning on performance and aerodynamic parameters of transonic axial-flow compressor rotors was studied. To understand all effects of lean angle, an organized investigation including numerical simulation of basic rotor, implementation of curvatures on basic rotor, numerical simulation of leaned blades and optimization were applied. Various levels of lean angles were implemented to basic rotor and by employing a three dimensional compressible turbulent model, the operating parameters were achieved. Afterwards, the results were used as input data of optimization computer code.

Finally, the ANN optimization method was used to achieve maximum stage pressure ratio, efficiency and safe operating range. it was found that the Optimized leaned blades according to their target function had positive or negative optimized angles and the optimized lean angles effectively increased the safe operating range about 12% and simultaneously increase the pressure ratio and efficiency by 4% and 5%, respectively.
A Numerical Investigation of Loss Coefficient Variation in Various Incidence Angles in Tandem Blades Cascade
Authors: Dehkharqani Arash Soltani , Boroomand Masoud , Eshraghi Hamzeh
Published: March 2015

There is a severe tendency to reduce weight and increase power of gas turbine. Such a requirement is fulfilled by higher pressure ratio of compressor stages. Employing tandem blades in multi-stage axial flow compressors is a promising methodology to control separation on suction sides of blades and simultaneously implement higher turning angle to achieve higher pressure ratio. The present study takes into account the high flow deflection capabilities of the tandem blades consisting of NACA-65 airfoil with fixed percent pitch and axial overlap at various flow incidence angles. In this regard, a two-dimensional cascade model of tandem blades is constructed in a numerical environment. The inlet flow angle is varied in a wide range and overall loss coefficient and deviation angles are computed. Moreover, the flow phenomena between the blades and performance of both forward and afterward blades are investigated. At the end, the aerodynamic flow coefficient of tandem blades are also computed with equivalent single blades to evaluate the performance of such blades in both design and off-design domain of operations. The results show that tandem blades are quite capable of providing higher deflection with lower loss in a wide range of operation and the base profile can be successfully used in design of axial flow compressor. In comparison to equivalent single blades, tandem blades have less dissipation because the momentum exerted on suction side of tandem blades confines the size of separation zone near trailing edges of blades.
Minimal Kinematic Model for Inverse Dynamic Analysis of Gait
Authors: Varma D. S. Mohan , Sujatha S.
Published: March 2015

The objective of this work is to develop an inverse dynamics model that uses minimal kinematic inputs to estimate the ground reaction force (GRF). The human body is modeled with 14 rigid segments and a circular ankle-foot-roll-over shape (AFROS) for the foot-ground interaction. The input kinematic data and body segment parameter estimates are obtained from literature. Optimization is used to ensure that the kinematic data satisfy the constraint that the swing leg clears the ground in the single support (SS) phase. For the SS phase, using the segment angles as the generalized degrees of freedom (DOF), the kinematic component of the GRF is expressed analytically as the summation of weighted kinematics of individual segments. The weighting functions are constants that are functions of the segment masses and center of mass distances. Using this form of the equation for GRF, it is seen that the kinematics of the upper body segments do not contribute to the vertical component GRFy in SS phase enabling the reduction of a 16-DOF 14-segment model to a 10-DOF 7-segment model. It is seen that the model can be further reduced to a 3-DOF model for GRFy estimation in the SS phase of gait. The horizontal component GRFx is computed assuming that the net GRF vector passes through the center of mass (CoM). The GRF in double support phase is assumed to change linearly from one foot to the other. The sagittal plane internal joint forces and moments acting at the ankle, knee and hip are computed using the 3-DOF model and the 10-DOF model and compared with the results from literature. An AFROS and measurements of the stance shank and thigh rotations in the sagittal plane, and of the lower trunk (or pelvis) in the frontal plane provide sufficient kinematics in an inverse dynamics model to estimate the GRF and joint reaction forces and moments. Such a model has the potential to simplify gait analysis.
Effects of UV Light and Moisture Absorption on the Impact Resistance of Three Different Carbon Fiber-Reinforced Composites
Authors: Patlolla V. , George J. , Loo Soo-Han , Asmatulu R.
Published: March 2015

The purpose of this research was to determine the influence of material properties on the impact response of a laminate, whereby specimens were fabricated and cured under a vacuum and high temperature using three types of pre-impregnated (prepreg), carbon fibers, namely unidirectional fiber, plain weave woven fiber, and non-crimp fiber (NCF). Each carbon fiber panel, usually known for its low-impact properties, of 16 plies underwent impact testing using a low-velocity impactor and visual damage inspection by C-scan in order to measure the damage area and depth, before and after impact testing. These panels were treated with UV exposure and moisture conditioning for 20 days each. Water contact angles were taken into consideration to determine the hydrophobicity and hydrophillicity of the respective prepreg materials. Experimental results and damage analysis showed that UV exposure and moisture conditioning showcased the variation in impact response and behavior, such as load-carrying capacity, absorbed energy, and impact energy of the carbon fiber panels. This study illustrates that non-crimp carbon fiber laminates were far more superior relative to load capacity than woven and unidirectional laminates, with the NCF-AS laminate exhibiting the highest load capacity of 17,244 lb/in (pre-UV) with only 0.89% decrease after UV exposure. This same laminate also had a 1.54% decrease in sustaining impact and 31.4% increase in wettability of the panel. Moreover, the study shows how symmetric and asymmetric stacking sequences affect the impact behavior of non-crimp fiber laminates. These results may be useful for expanding the capacity of carbon fiber, lowering costs, and growing new markets, thus turning carbon fiber into a viable commercial product.
Torsional Vibration Control of a Hooke’s Joint Driven Flexible Shaft System
Authors: Asokanthan Samuel F. , Wang Xiao-Hui , Baik Seung-Hoon
Published: March 2015

Torsional vibration control of a rotating mechanical system which incorporates a Hooke’s joint is investigated by pole assignment techniques. Linearized analytical models for the torsional system are established for the purposes of controller design. The resulting two-degree-of-freedom rotational system which contains time varying coefficients is parametrically excited due to an inherent non-linear velocity ratio across the Hooke’s joint. The controller is designed via full state feedback and observer based feedback in the transformed domain, using Lyapunov transformation. This transformation reduces the original time-varying system to a form suitable for controller design. A dual-system approach is employed to calculate the observer gain matrix for the time-varying system. Numerical simulation results show that the proposed control method is effective for suppressing torsional vibration of a Hooke’s joint driven system.
Investigation of Inducing Vibration to Reduce Friction of Coiled Tubing in Deep Drilling Operations
Authors: Abdo Jamil , Al-Sharji Hamed
Published: March 2015

This work examines the buckling behavior of constrained horizontal tubular in a cylinder subjected to axial compression force. Such configurations are of interest to coiled tubing (CT) and conventional hydrocarbon drilling. When compression force is applied beyond a critical value the coiled tubing (CT) will buckle forming sinusoidal wave and with increasing the load the CT ultimately goes into a helical configuration. The friction is introduced due to the contact between the CT and the borehole wall. Increasing the CT friction eventually leads to lock-up length beyond which the drilling cannot proceed further. Vibration is a well-known technique to reduce friction between contacting bodies in many engineering systems. An in-house experimental setup is developed to imitate the wellbore being drilled with the presence of drilling fluids and vibrating facility that has the capability to vibrate the CT axially. The setup is employed to examine the effects of amplitude and frequency of vibration on the axial force transfer and weight on bit (WOB) at normal and high temperature environments. Results show that both amplitude and frequency have significant effects in reducing the friction and they alter the buckling behavior on both normal and high temperature.
Virtual Airway Pressure and Lung Temperature Sensors in a Total Liquid Ventilation Connector
Authors: Robert Raymond , Micheau Philippe , Nadeau Mathieu , Vandamme Jonathan , Mousseau Julien , Avoine Olivier , Sage Michael , Praud Jean-Paul , Walti Hervé
Published: March 2015

Total liquid ventilation (TLV) is an experimental mechanical ventilation technique where the lungs are completely filled with a perfluorocarbon liquid (PFC). It can be used to implement moderate therapeutic hypothermia (MTH) and treat severe respiratory problems. During TLV, the airway pressure must be monitored adequately to avoid overpressure and airway collapses. On the thermodynamic level, rectal, esophageal or tympanic temperature measurements are not suitable (long time constant) to avoid lowering the heart below 30°C. The objective was to design a Y connector positioned at the mouth which integrates the virtual sensors, used by controllers. The first estimates the airway pressure and the second provides the core body temperature. Pressure and RTD sensors were installed in the connector to implement the virtual measurements. In-vitro experiments were done to validate the virtual sensors. In-vivo experiments (on newborn lambs) confirm the accuracy of the airway pressure estimation and of the systemic arterial temperature.
Dynamic Modeling of a Piggybacked Cantilever Beam System
Authors: Lundstrom Troy , Jalili Nader
Published: March 2015

Typically, active resonators for vibration suppression of flexible systems are uniaxial and can only affect structure response in the direction of the applied force. The application of piezoelectric bender actuators as active resonators may prove to be advantageous over typical, uniaxial actuators as they can dynamically apply both torque and translational force to the base structure attachment point; this minimizes the likelihood that the attachment location is the node of a mode (rotary or translational). In this paper, Hamilton’s Principle is used to develop the equations of motion for a continuous two-beam system composed of a cantilevered, primary base beam with a secondary piezoelectric bender mounted to its surface. A disturbance force is applied near the fixture location of the base beam and the system response is estimated using a sufficient quantity of assumed eigenfunctions that satisfy the geometric boundary conditions. A theoretical study is performed to compared the continuous system eigenfunctions to a finite element model (FEM) of the two-beam structure and the required number of eigenfunctions required to yield a convergent solution for an impulse excitation is explored. In addition, the frequency response function for the dynamic system is presented and compared to that of a FEM.
Developing a Physical Model of an Electromechanically Actuated Valve to Model Valve Disease In Vitro
Authors: Manthripragada Krishna Chaitanya , Lagarde Chandler P. , Taylor Charles E.
Published: March 2015

Onset of valve disease, mainly stenosis, is common in post left ventricular assist device (LVAD) implantation. Hydraulically, this condition manifests itself as a change in the opening profile of the heart valve; smaller effective hydraulic diameters. Studying the onset of this disease during mock circulatory loop analysis of an LVAD design enables the cardiovascular condition changes to be more appropriately modeled. This would provide insight to the impact on changes in operating demands for a device over the course of its use; power demand and performance impact. The challenge of producing a valve that can control its opening profile to mimic both healthy and stenosis states is difficult due to the low valve differential pressures experienced in vivo (<1 psi). A novel design of a mono-leaflet swing valve that is electromechanically actuated is being developed to simulate onset of stenosis in a human aortic valve. Finite element analysis (FEA) was employed to produce a computational fluid dynamics (CFD) model of the design for the purpose of estimating the torque delivered to the actuator by the fluid flow against the leaflet. Modeling a wide range of flow rates through various valve angles of operation provided data on the full operating range for the device. Calculation of the torque on the driveshaft manipulating the leaflet angle was derived from pressure data for 38 points on the valve’s surface. Utilizing this data in a Simulink Simscape physical model of the electromechanical system enables accurate control architecture to be developed for the device through the use of design optimization. Discussion of the CFD model results and how to employ them in the Simscape model will be discussed. Performance of the physical model in a pulsatile flow study, analogous to the human circulatory system, will be presented illustrating the ability of the design to model onset of stenosis in an aortic valve.
Boundary Control of a Marine Riser Pipe Conveying Fluid
Authors: Nojoumian M. A. , Shirazi M. Jahromi , Salarieh H.
Published: March 2015

In this paper, the model of pipe conveying fluid, like marine risers, is modeled with the effect of the interaction between the fluid and structure. A torque is assumed at one end of the pipe to control the vibration of the pipe. The stability of the pipe under time varying disturbance in forced vibration using boundary control law is proved. Exponential stability can be achieved under the free vibration condition. The proposed control law is simple and could be attained by some simple sensors at the end of the pipe. The control law is independent from system parameters so the controller is robust to disturbances and environmental conditions. The controller is obtained via a Lyapunov function in PDE form. Numerical simulations are used to verify the effectiveness of the proposed method.
Development of a Dynamic Knee Actuator for a KAFO Using Superelastic Alloys
Authors: Tian Feng , Hefzy Mohamed Samir , Elahinia Mohammad
Published: March 2015

A knee-ankle-foot orthosis (KAFO), which covers the knee, ankle and foot, can mitigate abnormal walking pattern caused by weak quadriceps. Several types of KAFOs are currently available in the market: passive KAFOs, stance-control KAFOs and dynamic KAFOs. In passive KAFOs, the knee joint keeps being locked during standing and walking, and can be unlocked manually to allow free rotation for sitting. Stance-control KAFOs (SCKAFOs) allow free knee motion during swing phase when the braced leg is unloaded. Dynamic KAFOs are able to reproduce normal walking ability throughout whole gait cycle. This research is directed at using superelastic alloys to develop a dynamic knee actuator that can be mounted on a traditional passive KAFO. The actuator stiffness can match that of a normal knee joint during the walking gait cycle. This proposed knee actuator utilizes a storing-releasing energy method to apply functional compensation to the knee joint, controlling the knee joint during both stance and swing phases. Fundamentally, the knee actuator is composed of two distinct parts which are connected with the thigh and shank segments, respectively. There are two superelastic actuators that are housed within these two parts and activated independently. Each actuator is developed by combining a superelastic rod and a rotary spring in series. When neither actuator is engaged, the knee joint is allowed to rotate freely. The stance actuator works only in the stance phase and the swing actuator is active for the swing phase. The conceptual design of the knee actuator is verified using numerical simulation and a prototype is developed through additive manufacturing for confirming the concept.
Resolution and alignment accuracy of low-temperature in situ electron beam lithography for nanophotonic device fabrication
Authors: Gschrey Manuel , Schmidt Ronny , Schulze Jan-Hindrik , Strittmatter André , Rodt Sven , Reitzenstein Stephan
Published: March 2015

The performance of a deterministic lithographic technology to produce a reliable and accurate fabrication of nanophotonic devices based on epitaxial quantum dots is analyzed. Directly after the selection of qualified quantum dots by low-temperature cathodoluminescence spectroscopy in a scanning electron microscope, the in situ electron beam lithography step is performed. In an optimized process flow, quantum dot positions are identified with an accuracy of 25 nm, and a nanoscale alignment accuracy of the device structures of 24 nm for the emitters and one as low as 65 nm for feature sizes is demonstrated. Such accuracies surpass the performance of previously developed optical in situ lithography techniques, making this site control of quantum dots appropriate deterministic quantum device fabrication.
GPU‐accelerated regularized iterative reconstruction for few‐view cone beam CT
Authors: Matenine Dmitri , Goussard Yves , Després Philippe
Published: March 2015

Purpose:

The present work proposes an iterative reconstruction technique designed for x‐ray transmission computed tomography (CT). The main objective is to provide a model‐based solution to the cone‐beam CT reconstruction problem, yielding accurate low‐dose images via few‐views acquisitions in clinically acceptable time frames.

Methods:

The proposed technique combines a modified ordered subsets convex (OSC) algorithm and the total variation minimization (TV) regularization technique and is called OSC‐TV. The number of subsets of each OSC iteration follows a reduction pattern in order to ensure the best performance of the regularization method. Considering the high computational cost of the algorithm, it is implemented on a graphics processing unit, using parallelization to accelerate computations.

Results:

The reconstructions were performed on computer‐simulated as well as human pelvic cone‐beam CT projection data and image quality was assessed. In terms of convergence and image quality, OSC‐TV performs well in reconstruction of low‐dose cone‐beam CT data obtained via a few‐view acquisition protocol. It compares favorably to the few‐view TV‐regularized projections onto convex sets (POCS‐TV) algorithm. It also appears to be a viable alternative to full‐dataset filtered backprojection. Execution times are of 1–2 min and are compatible with the typical clinical workflow for nonreal‐time applications.

Conclusions:

Considering the image quality and execution times, this method may be useful for reconstruction of low‐dose clinical acquisitions. It may be of particular benefit to patients who undergo multiple acquisitions by reducing the overall imaging radiation dose and associated risks.
Genome Sequence of Acinetobacter baumannii Strain A1, an Early Example of Antibiotic-Resistant Global Clone 1
Authors: Holt Kathryn E. , Hamidian Mohammad , Kenyon Johanna J. , Wynn Matthew T. , Hawkey Jane , Pickard Derek , Hall Ruth M.
Published: March 2015

Acinetobacter baumannii
isolate A1 was recovered in the United Kingdom in 1982 and belongs to global clone 1 (GC1). Here, we present its complete 3.91-Mbp genome sequence, generated via a combination of short-read sequencing (Illumina), long-read sequencing (PacBio), and manual finishing.
Draft Genome Sequence of Nocardia seriolae Strain N-2927 (NBRC 110360), Isolated as the Causal Agent of Nocardiosis of Yellowtail (Seriola quinqueradiata) in Kochi Prefecture, Japan
Authors: Imajoh Masayuki , Fukumoto Yoichi , Yamane Jin , Sukeda Masaki , Shimizu Masato , Ohnishi Kouhei , Oshima Syun-ichirou
Published: March 2015

We report the draft genome sequence of
Nocardia seriolae
strain N-2927 (NBRC 110360), isolated from cultured yellowtail
Seriola quinqueradiata
. RAST annotation of the genome revealed 117 genes involved in the virulence, disease, and defense subsystem. Eleven of these genes were predicted as antibiotic resistance genes.
Draft Genome Sequence of Lactobacillus plantarum Lp90 Isolated from Wine
Authors: Lamontanara Antonella , Caggianiello Graziano , Orrù Luigi , Capozzi Vittorio , Michelotti Vania , Bayjanov Jumamurat R. , Renckens Bernadet , van Hijum Sacha A. F. T. , Cattivelli Luigi , Spano Giuseppe
Published: March 2015

Here, we describe the draft genome sequence and annotation of
Lactobacillus plantarum
strain Lp90, the first sequenced genome of a L. plantarum strain isolated from wine. This strain has a noticeable ropy phenotype and showed potential probiotic properties. The genome consists of 3,324,076 bp (33 contigs) and contains 3,155 protein coding genes, 34 pseudogenes, and 84 RNA genes.
Draft Genome Sequences of Gammaproteobacterial Methanotrophs Isolated from Lake Washington Sediment
Authors: Kalyuzhnaya Marina G. , Lamb Andrew E. , McTaggart Tami L. , Oshkin Igor Y. , Shapiro Nicole , Woyke Tanja , Chistoserdova Ludmila
Published: March 2015

The genomes of
Methylosarcina lacus
LW14
T
(=ATCC BAA-1047
T
= JCM 13284
T
), Methylobacter sp. strain 21/22, Methylobacter sp. strain 31/32, Methylomonas sp. strain LW13, Methylomonas sp. strain MK1, and Methylomonas sp. strain 11b were sequenced and are reported here. All the strains are obligately methanotrophic bacteria isolated from the sediment of Lake Washington.
Genome Sequences of Equid Herpesviruses 2 and 5
Authors: Wilkie Gavin S. , Kerr Karen , Stewart James P. , Studdert Michael J. , Davison Andrew J.
Published: March 2015

We resequenced the genome of equid herpesvirus 2 (EHV2) strain 86/67 and sequenced the genomes of EHV2 strain G9/92 and equid herpesvirus 5 (EHV5) strain 2-141/67. The most prominent genetic differences are the dissimilar locations of the interleukin-10 (IL-10)-like genes and the presence of an OX-2-like gene in EHV5 only.
Associations between heart rate variability, metabolic syndrome risk factors, and insulin resistance
Authors: Stuckey Melanie I. , Kiviniemi Antti , Gill Dawn P. , Shoemaker J. Kevin , Petrella Robert J.
Published: March 2015

The purpose of this study was to examine differences in heart rate variability (HRV) in metabolic syndrome (MetS) and to determine associations between HRV parameters, MetS risk factors, and insulin resistance (homeostasis model assessment for insulin resistance (HOMA-IR)). Participants (n = 220; aged 23–70 years) were assessed for MetS risk factors (waist circumference, blood pressure, fasting plasma glucose, triglycerides, and high-density lipoprotein cholesterol) and 5-min supine HRV (time and frequency domain and nonlinear). HRV was compared between those with 3 or more (MetS+) and those with 2 or fewer MetS risk factors (MetS–). Multiple linear regression models were built for each HRV parameter to investigate associations with MetS risk factors and HOMA-IR. Data with normal distribution are presented as means ± SD and those without as median [interquartile range]. In women, standard deviation of R–R intervals 38.0 [27.0] ms, 44.5 [29.3] ms; p = 0.020), low-frequency power (5.73 ± 1.06 ln ms2, 6.13 ± 1.05 ln ms2; p = 0.022), and the standard deviation of the length of the Poincaré plot (46.8 [31.6] ms, 58.4 [29.9] ms; p = 0.014) were lower and heart rate was higher (68 [13] beats/min, 64 [12] beats/min; p = 0. 018) in MetS+ compared with MetS–, with no differences in men. Waist circumference was most commonly associated with HRV, especially frequency domain parameters. HOMA-IR was associated with heart rate. In conclusion, MetS+ women had a less favourable HRV profile than MetS– women, but there were no differences in men. HOMA-IR was associated with heart rate, not HRV.
On topological indices of poly oxide, poly silicate, DOX, and DSL networks
Authors: Baig Abdul Qudair , Imran Muhammad , Ali Haidar
Published: March 2015

Topological indices are numerical parameters of a graph that characterize its topology and are usually graph invariant. In a QSAR/QSPR study, physicochemical properties and topological indices such as Randić, atom–bond connectivity (ABC), and geometric–arithmetic (GA) indices are used to predict the bioactivity of chemical compounds. Graph theory has found a considerable use in this area of research. In this paper, we study different interconnection networks and derive analytical closed results of the general Randić index (Rα(G)) for α = 1, [Formula: see text], –1, [Formula: see text] only, for dominating oxide network (DOX), dominating silicate network (DSL), and regular triangulene oxide network (RTOX). All of the studied interconnection networks in this paper are motivated by the molecular structure of a chemical compound, SiO4. We also compute the general first Zagreb, ABC, GA, ABC4, and GA5 indices and give closed formulae of these indices for these interconnection networks.
Theoretical investigations of charge carrier transport in organic semiconductors of naphthalene bisimides N-substituted with alkoxyphenyl groups
Authors: Yin Jun , Chaitanya Kadali , Ju Xue-Hai
Published: March 2015

Three novel alkoxyphenyl N-substituted naphthalene bisimide derivatives, N,N′-bis(4-n-butoxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI1), N,N′-bis(4-n-hexyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI2), and N,N′-bis(4-n-octyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI3) as potential organic semiconductors, have been investigated using density functional theory calculations coupled with the incoherent charge-hopping model at the molecular and crystal levels. The calculated results demonstrate that the low-lying and delocalized LUMOs and larger adiabatic electron affinities of these compounds are beneficial to their stability when acting as n-type organic semiconductors. The reorganization energy and transfer integral can significantly influence the charge carrier mobility. The compounds featured with the small reorganization energy and large transfer integral have relatively high charge mobilities. The electron coupling among the dominant hopping pathways indicates that the charge-transport processes happen in the parallel dimer of neighboring molecules with π–π interaction. The investigation of the angle dependence of charge carrier mobility showed that both NBI1 and NBI3 crystals exhibit remarkable anisotropic charge transporting behaviors. The calculated absorption spectra by the time-dependent density functional theory revealed that the strongest absorption peaks in the visible region are assigned to the π → π* transition and these peaks are regulated by the transitions of HOMO → LUMO. The calculated electron mobilities of NBI1, NBI2, and NBI3 are 0.0365, 0.0312, and 0.0801 cm2 V–1 s–1, respectively, indicating that these compounds are suitable for n-type organic semiconductors.
Dynamic hypoxic zones in Lake Erie compress fish habitat, altering vulnerability to fishing gears
Authors: Kraus Richard T. , Knight Carey T. , Farmer Troy M. , Gorman Ann Marie , Collingsworth Paris D. , Warren Glenn J. , Kocovsky Patrick M. , Conroy Joseph D.
Published: March 2015

Seasonal degradation of aquatic habitats from hypoxia occurs in numerous freshwater and coastal marine systems and can result in direct mortality or displacement of fish. Yet, fishery landings from these systems are frequently unresponsive to changes in the severity and extent of hypoxia, and population-scale effects have been difficult to measure except in extreme hypoxic conditions with hypoxia-sensitive species. We investigated fine-scale temporal and spatial variability in dissolved oxygen in Lake Erie as it related to fish distribution and catch efficiencies of both active (bottom trawls) and passive (trap nets) fishing gears. Temperature and dissolved oxygen loggers placed near the edge of the hypolimnion exhibited much higher than expected variability. Hypoxic episodes of variable durations were frequently punctuated by periods of normoxia, consistent with high-frequency internal waves. High-resolution interpolations of water quality and hydroacoustic surveys suggest that fish habitat is compressed during hypoxic episodes, resulting in higher fish densities near the edges of hypoxia. At fixed locations with passive commercial fishing gear, catches with the highest values occurred when bottom waters were hypoxic for intermediate proportions of time. Proximity to hypoxia explained significant variation in bottom trawl catches, with higher catch rates near the edge of hypoxia. These results emphasize how hypoxia may elevate catch rates in various types of fishing gears, leading to a lack of association between indices of hypoxia and fishery landings. Increased catch rates of fish at the edges of hypoxia have important implications for stock assessment models that assume catchability is spatially homogeneous.
Deformation of second and third quantization
Authors: Faizal Mir
Published: March 2015

In this paper, we will deform the second and third quantized theories by deforming the canonical commutation relations in such a way that they become consistent with the generalized uncertainty principle. Thus, we will first deform the second quantized commutator and obtain a deformed version of the Wheeler–DeWitt equation. Then we will further deform the third quantized theory by deforming the third quantized canonical commutation relation. This way we will obtain a deformed version of the third quantized theory for the multiverse.
Outlier Detection in the Framework of Dimensionality Reduction
Authors: Ye Qiang , Zhi Weifeng
Published: March 2015

We propose an effective outlier detection algorithm for high-dimensional data. We consider manifold models of data as is typically assumed in dimensionality reduction/manifold learning. Namely, we consider a noisy data set sampled from a low-dimensional manifold in a high-dimensional data space. Our algorithm uses local geometric structure to determine inliers, from which the outliers are identified. The algorithm is applicable to both linear and nonlinear models of data. We also discuss various implementation issues and we present several examples to demonstrate the effectiveness of the new approach.
Feynman approximation to integrals with respect to Brownian sheet on Lie groups
Authors: Kalinichenko A. A.
Published: March 2015

We consider the Feynman-type approximations to functional integrals over the distribution of the Brownian sheet on a compact connected Lie group M, which give a representation of the integrals over the functional space C([0, 1] × [0, 1], M) as the limit of integrals over the finite-dimensional manifolds M × ⋯ × M. The known approximation formulas for the one-parameter Brownian motion are generalized to the case of the Brownian sheet.
A Study on Unobserved Structural Innovations of Oil Price: Evidence from Global Stock, Bond, Foreign Exchange, and Energy Markets
Authors: Baek Jungho , Seo Ji-Yong
Published: March 2015

This study examines the effects of oil shocks by their respective causes and of volatility spillover including leverage effects. Previous studies did not analyze oil factor by categorizing it into three components (supply shock, demand shock, and market shock) as determinants of rate of return in stock markets, a key issue in finance. Results show that oil shocks determine returns in the global stock market, bond market, foreign exchange market, and energy market, and that their effects vary by types of markets, levels of oil prices, and types of oil shocks. Second, the leverage effect of oil shocks and the spillover effect of volatility in demand shock and market shock are mostly statistically significant during periods characterized by high oil prices.
Level and Determinants of Foreign Bank Efficiency in a Pacific Island Country
Authors: Sharma Parmendra , Gounder Neelesh , Xiang Dong
Published: March 2015

This study fills a huge gap in literature by providing some evidence on the level and determinants of bank efficiency in a Pacific island context. DEA results show that overall efficiency levels may be lower than in Australia, the home country of major banks. Dynamic GMM and panel data results show that personnel expenses and bank credit matter for efficiency, but not other bank-specific and macroeconomic factors. These insights substantially improve policy-making capacities for Fiji and other Pacific economies, including Papua New Guinea, Samoa, Tonga, Solomon Islands and Vanuatu where banking and regulatory systems and structures are highly comparable.
Sign-changing tower of bubbles for the Brezis–Nirenberg problem
Authors: Iacopetti Alessandro , Vaira Giusi
Published: March 2015

In this paper, we prove that the Brezis–Nirenberg problem: [Formula: see text] where [Formula: see text] is a symmetric bounded smooth domain in [Formula: see text], [Formula: see text] and [Formula: see text], has a solution with the shape of a tower of two bubbles with alternate signs, centered at the center of symmetry of the domain, for all [Formula: see text] sufficiently small.
An approach without using Hardy inequality for the linear heat equation with singular potential
Authors: Ferreira Lucas C. F. , Mesquita Cláudia Aline A. S.
Published: March 2015

The aim of this paper is to employ a strategy known from fluid dynamics in order to provide results for the linear heat equation ut- Δu - V(x)u = 0 in ℝnwith singular potentials. We show well-posedness of solutions, without using Hardy inequality, in a framework based in the Fourier transform, namely, PMk-spaces. For arbitrary data u0∈ PMk, the approach allows to compute an explicit smallness condition on V for global existence in the case of V with finitely many inverse square singularities. As a consequence, well-posedness of solutions is obtained for the case of the monopolar potential [Formula: see text] with [Formula: see text]. This threshold value is the same one obtained for the global well-posedness of L2-solutions by means of Hardy inequalities and energy estimates. Since there is no any inclusion relation between L2and PMk, our results indicate that λ*is intrinsic of the PDE and independent of a particular approach. We also analyze the long-time behavior of solutions and show there are infinitely many possible asymptotics characterized by the cells of a disjoint partition of the initial data class PMk.
Parameter estimation of qubit states with unknown phase parameter
Authors: Suzuki Jun
Published: March 2015

We discuss a problem of parameter estimation for quantum two-level system, qubit system, in presence of unknown phase parameter. We analyze trade-off relations for mean square errors (MSEs) when estimating relevant parameters with separable measurements based on known precision bounds; the symmetric logarithmic derivative (SLD) Cramér–Rao (CR) bound and Hayashi–Gill–Massar (HGM) bound. We investigate the optimal measurement which attains the HGM bound and discuss its properties. We show that the HGM bound for relevant parameters can be attained asymptotically by using some fraction of given n quantum states to estimate the phase parameter. We also discuss the Holevo bound which can be attained asymptotically by a collective measurement.
Cayley formula in Minkowski space-time
Authors: Erdoğdu Melek , Özdemir Mustafa
Published: March 2015

In this paper, Cayley formula is derived for 4 × 4 semi-skew-symmetric real matrices in [Formula: see text]. For this purpose, we use the decomposition of a semi-skew-symmetric matrix A = θ1A1+ θ2A2by two unique semi-skew-symmetric matrices A1and A2satisfying the properties [Formula: see text] and [Formula: see text] Then, we find Lorentzian rotation matrices with semi-skew-symmetric matrices by Cayley formula. Furthermore, we give a way to find the semi-skew-symmetric matrix A for a given Lorentzian rotation matrix R such that R = Cay (A).
EXPLORATION AND EXPLOITATION IN SCIENCE: THEIR IMPACT ON SCIENTIFIC AND TECHNOLOGICAL OUTCOMES
Authors: MCMILLAN G. STEVEN
Published: March 2015

Since March's 1991 seminal article, exploration and exploitation have been extensively studied in the areas of organisational learning, strategic renewal, and technological innovation [Li et al.(2008)]. However, much of the research has focused on exploration as science-based and exploitation as technology-based. This current research effort utilises a unique database to examine the phenomena only in the science arena. The results are that exploration efforts lead to science outcomes, and that both exploration and exploitation efforts have a positive impact on technological outcomes. The managerial implications of these findings are discussed.
DEVELOPING COUNTRIES' RESPONSE TO THE CLEAN DEVELOPMENT MECHANISM UNDER IMPERFECT INFORMATION AND TRANSACTION COSTS
Authors: HONLONKOU ALBERT N. , HASSAN RASHID M.
Published: March 2015

Developing countries are struggling for finding resources to finance their adaptation to or mitigation of the effects of climate change. In that spirit, the Copenhagen summit, the fifteenth Conference of Parties (COP15) can be seen as a success since it ended with an important promise of creation of a common fund of $US 100 billions per year over the period 2013–2020 to help poor and emerging countries to support adoption of costly but eco-friendly technologies. However, implementation of former instruments shows mixed results. In this paper, we show that transaction costs effect dominates asymmetric information effect in impeding some developing countries to benefit from the clean development mechanism, one of the instruments of the implementation of the Kyoto Protocol. Thus environmental instruments may be useless if they are not supplemented by policies to reduce transaction costs in the host countries.
Polychlorinated biphenyl quinone induces endothelial barrier dysregulation by setting the cross talk between VE-cadherin, focal adhesion, and MAPK signaling
Authors: Zhang Pu , Feng Shan , Bai Huiyuan , Zeng Panying , Chen Feng , Wu Chengxiang , Peng Yi , Zhang Qin , Zhang Qiuyao , Ye Qichao , Xue Qiang , Xu Xiaoyu , Song Erqun , Song Yang
Published: March 2015

Environmental hazardous material polychlorinated biphenyl (PCB) exposure is associated with vascular endothelial dysfunction, which may increase the risk of cardiovascular diseases and cancer metastasis. Our previous studies illustrated the cytotoxic, antiproliferative, and genotoxic effects of a synthetic, quinone-type, highly reactive metabolite of PCB, 2,3,5-trichloro-6-phenyl-[1,4]benzoquinone (PCB29-pQ). Here, we used it as the model compound to investigate its effects on vascular endothelial integrity and permeability. We demonstrated that noncytotoxic doses of PCB29-pQ induced vascular endothelial (VE)-cadherin junction disassembly by increasing the phosphorylation of VE-cadherin at Y658. We also found that focal adhesion assembly was required for PCB29-pQ-induced junction breakdown. Focal adhesion site-associated actin stress fibers may serve as holding points for cytoskeletal tension to regulate the cellular contractility. PCB29-pQ exposure promoted the association of actin stress fibers with paxillin-containing focal adhesion sites and enlarged the size/number of focal adhesions. In addition, PCB29-pQ treatment induced phosphorylation of paxillin at Y118. By using pharmacological inhibition, we further demonstrated that p38 activation was necessary for paxillin phosphorylation, whereas extracellular signal-regulated kinases-1/2 activation regulated VE-cadherin phosphorylation. In conclusion, these results indicated that PCB29-pQ stimulates endothelial hyperpermeability by mediating VE-cadherin disassembly, junction breakdown, and focal adhesion formation. Intervention strategies targeting focal adhesion and MAPK signaling could be used as therapeutic approaches for preventing adverse cardiovascular health effects induced by environmental toxicants such as PCBs.