bluuebunny/crossref_metadata_2025 huggingface dataset:
User Defined Assembly Features and Pattern Recognition From STEP AP203
Authors: Vemulapalli Prabath , Mohan Prashant , Shah Jami J. , Davidson Joseph K.
Published: January 2015

Tolerance allocation is important aspect in designing as well as manufacturing. Mating features in an assembly are important from the tolerance point of view and govern the tolerance schema. Presence of patterns within these features also plays an important role in the allocation of different tolerance classes. Identification of these assembly features and patterns are previously done manually. This research is aimed at automating these processes. The automation starts with the recognition of the assembly features in the assembly. The algorithms for feature recognition are designed such that they can handle any user defined assembly feature. The input for feature recognition is a STEP file containing information of the assembly. And the output file contains information of the recognized assembly features. Then patterns are identified from these assembly features. This paper discusses these two processes in detail. Also to facilitate the user, define new assembly features an alternate system called assembly feature tutor is developed. This paper also explains the working of this tutor.
Automatic Detection and Extraction of Tolerance Stacks in Mechanical Assemblies
Authors: Haghighi Payam , Mohan Prashant , Shah Jami J. , Davidson Joseph K.
Published: January 2015

Tolerances are specified by a designer to allow reasonable freedom by a manufacturer for imperfections and inherent variability without compromising performance. It takes knowledge and experience to create a good tolerance scheme. It is a tedious process driven by the type of parts, their features and controls needed for each one of them. In this paper, we investigate the extent to which GD&T schema development can be automated. Automated tolerance schema generation, requires identifying critical tolerance loops. The tolerance loop is a loop of dimensions between faces of features governing assembly conditions. For this purpose, the first major step is to identify mating features called assembly features. Also, in order to create the tolerance chains we need Local Constraints (assembly feature relationships), Global constraints (part feature relationships) and directions of control. In addition, we have to identify feature patterns since they have associated tolerances according to Dimensioning and Tolerancing Standard ASME Y14.5M. Directions in which these loops lie are also needed; we call them Direction of Control (DoC). Then we can create the GD&T schema, allocate tolerance values, and prepare it for tolerance evaluation. In this paper, we present an approach to automatically identify the dimensional loops based on assembly requirements. Assignment of tolerance values will be covered in future works as it is based on design function.
Effects of Over-the-Counter Medication Product Family Packaging Design on Knowledge Acquisition and Consumer Preferences
Authors: Cho Jay , Miller Scarlett R. , Simpson Timothy W. , Shooter Steven B.
Published: January 2015

Adverse drug events result in hospitalization of more than 1.5 million Americans each year leading to large increases in health care costs. Although researchers have shown that a large portion of these adverse drug events are preventable, most Americans admit to only reading portions of over-the-counter (OTC) labeling, and only half say they seek out information on the label for usage information when they take an OTC medication for the first time. It is important then that we carefully consider what packaging features can motivate consumers to more thoughtfully consider the use of the OTC medicine and how packaging commonality within a product family influences the correct selection of these medications. In order to understand these questions, a controlled study was conducted with sixty-four participants who were asked to complete a Short Test of Functional Health Literacy in Adults (s-TOFHLA), a medication selection questionnaire that required participants to select the appropriate medication based on a given set of symptoms, and a packaging label ratings questionnaire. Two medication brands with five different types of package designs were studied. Product family commonality metrics were used to analyze the similarity among these simulated products, and statistical analyses were performed on the selection time and accuracy data obtained. The results illustrated that variations in labeling and product family packaging design significantly impact the accuracy and efficiency of medication decision-making and thus has the potential to reduce adverse drug events made during the OTC medication selection process.
Theoretical Modeling of a Pressure-Operated Soft Snake Robot
Authors: Luo Ming , Agheli Mahdi , Onal Cagdas D.
Published: January 2015

This paper addresses the theoretical modeling of the dynamics of a pressure-operated soft snake robot. An accurate dynamic model is a fundamental requirement for optimization, control, navigation, and learning algorithms for a mobile robot that can undergo serpentine locomotion. Such algorithms can be readily implemented for traditional rigid robots, but remain a challenge for nonlinear and low-bandwidth soft robotic systems. A framework to solve the 2-D modeling problem of a soft robotic snake is detailed with a general approach applicable to most pressure-operated soft robots that are developed by a modular kinematic arrangement of bending-type fluidic elastomer actuators. The model is simulated using measured physical parameters of the robot and workspace. The theoretical results are verified through a proof-of-concept comparison to locomotion experiments on a flat surface with measured frictional properties. Experimental results indicate that the proposed model describes the motion of the robot.
An Origami Inspired Reconfigurable Spiral Antenna
Authors: Saintsing Christy D. , Cook Benjamin S. , Tentzeris Manos M.
Published: January 2015

Modern day systems often require reconfigurability in the operating parameters of the transmit and receive antennas, such as the resonant frequency, radiation pattern, impedance, or polarization. In this work a novel approach to antenna reconfigurability is presented by integrating antennas with the ancient art of origami. The proposed antenna consists of an inkjet printed center-fed spiral antenna, which is designed to resonate at 1.0GHz and have a reconfigurable radiation pattern while maintaining the 1.0GHz resonance with little variation in input impedance. When flat, the antenna is a planar spiral exhibiting a bidirectional radiation pattern. By a telescoping action, the antenna can be reconfigured into a conical spiral with a directional pattern and higher gain, which gives the antenna a large front-to-back ratio. Construction of the antenna in this manner allows for a simple, lightweight, transportable antenna that can expand to specifications in the field.
A Method for a More Accurate Calculation of the Stiffness Coefficient in a Pseudo-Rigid-Body Model (PRBM) of a Fixed-Free Beam Subjected to End Forces
Authors: Midha Ashok , Kuber Raghvendra S. , Chinta Vivekananda , Bapat Sushrut G.
Published: January 2015

The pseudo-rigid-body model (PRBM) concept allows compliant mechanisms to be modeled using existing knowledge of rigid-body mechanisms, thereby considerably simplifying their analysis and design. The PRBMs represent the compliant segments with two or more rigid-body segments, connected using pin joints (characteristic pivots). The beam compliance is modeled using a torsional spring placed at the characteristic pivot, whose spring constant K is evaluated using a pseudo-rigid-body parameter termed as the beam stiffness coefficient. This paper presents a method to more accurately calculate the beam stiffness coefficient for a fixed-free compliant beam subjected to a combination of horizontal and vertical forces. The improved stiffness coefficient (KΘ) expressions are derived as a function of the pseudo-rigid-body angle, Θ and the load factor, n. To exemplify the application of the improved results, the expressions derived are successfully implemented in modeling a fixed-guided beam with an inflection point, allowing it to be modeled as two fixed-free beams pinned at the inflection point.
Synthesis of an NR Robot With Four-Bar Constraining Modules
Authors: Tsuge Brandon Y. , McCarthy J. Michael
Published: January 2015

This paper uses coupler-path synthesis to design four-bar linkage modules that constrains the movement of links in an nR serial chain. The goal is to formulate a general procedure for path-synthesis of a robotic system using four-bar linkages. A desired end-effector trajectory is transformed into a secondary trajectory that is used for nine-point synthesis of a constraining four-bar linkage. This procedure constrains an nR chain to become a 4n-2 bar linkage. An example presents the constraint of a 2R chain to a six-bar that has a prescribed trajectory for an end-effector point.
Vehicle Suspension Design Based on a Six-Bar Linkage
Authors: Plecnik Mark M. , McCarthy J. Michael
Published: January 2015

A synthesis technique for designing novel vehicle suspension linkages based on the Watt I six-bar is presented. The goal is to maintain near vertical alignment of the wheels to the road during cornering. The complete suspension is analyzed as a symmetric planar 12-bar linkage with ground pivots located at the contact patches. The design procedure specifies the vehicle chassis orientation and the tire camber angles of the vehicle when cornering. As well, two task positions of the wheels with respect to the chassis are specified for suspension movement in straightaways. The result is 18 design equations with 18 unknowns that have a total degree of 2,097,152, though only 336 roots. An example design is presented.
Approximation and Control of Curvilinear Shapes via Deployable Mechanisms With Two Degrees of Freedom
Authors: Lu Shengnan , Zlatanov Dimiter , Ding Xilun , Molfino Rezia , Zoppi Matteo
Published: January 2015

This paper proposes a multi-unit mechanism, which can be used to approximate, with two independent degrees of freedom, the shape of the geometric outline of an arbitrarily large area. The new device is a variant of a recently introduced planar deployable mechanism with two uncoupled degrees of freedom, built from identical units, each combining Sarrus and scissor linkages. Similar units, but with varying sizes, are used in the new device, which is able to change its elliptical physical boundary by varying independently the two parameters in the standard ellipse equation. The size and placement of the deployable units and their links are analyzed and selected for getting the expected geometric shape. The relationships between the number of dividing lines and the approximating accuracy and the degree of overconstraint, respectively, are calculated. A similar deployable mechanism controlling a hyperbola is also outlined. Kinematic analysis and simulated models show that the mechanisms can be used to approximate geometric curves, as desired.
Evaluation of Human Thermal Comfort Using Near-Infrared Spectroscopy
Authors: Watanuki Keiichi , Hou Lei , Kondou Yuuki
Published: January 2015

Air-conditioning equipment is used in various places such as houses, office buildings, and public facilities and is indispensable in modern-day life. Therefore, the energy consumption of air-conditioning equipment accounts for a large percentage of the total energy consumption in the average household. Specifically, it accounts for 26% of the annual energy consumption in ordinary homes and 27% in industry, according to the Annual Energy Report for Japan, which was presented by the Ministry of the Economy, Trade, and Industry, and the Agency for Natural Resources and Energy in 2010. Therefore, it is desirable to reduce energy consumption by reducing the air-conditioning load. The Ministry of the Environment recommends a constant preset temperature of 28°C in summer to decrease energy consumption. However, many people feel uncomfortable in such a thermal environment. Thus, an air-conditioning control to simultaneously suppress energy consumption and maintain human thermal comfort is desired. To develop such a control, an index to accurately evaluate human thermal comfort is needed. When a person feels comfortable or uncomfortable, their prefrontal area, which is involved in thinking and the feeling of emotions, is activated. It is presumed that the measurement of the brain activation reaction of a person will reveal whether the person feels comfortable or uncomfortable in the thermal environment. The evaluation of thermal comfort by means of brain activation reactions will allow one to develop the optimum air-conditioning control to maintain human thermal comfort. This paper proposes a method to evaluate thermal comfort via brain signals and ultimately aims to develop an air-conditioning control system utilizing this evaluation method. This paper will describe the measurement procedure of brain activation reactions to indoor-temperature change by using near-infrared spectroscopy and the relationship between thermal comfort and brain activation reaction. This study also investigated the changes in oxyHb levels together with indoor-temperature changes, measured with the NIRS. We measured the changes in the oxyHb levels of the prefrontal area when the temperature increased and decreased. As a result, the oxyHb level in the prefrontal area correlated with the indoor-temperature change, the PMV, and the subjects’ declaration of thermal sensation. Conversely, the change in the oxyHb level with the inclusion of wind and a constant indoor temperature significantly differed with that with a varying indoor temperature. Furthermore, the oxyHb change correlated with the PMV and the subject’s declaration of thermal sensation. Therefore, the measured oxyHb change may represent the thermal comfort of a person.
Saline Solution Effects on Propidium Iodide Uptake in Nanoinjected HeLa Cells
Authors: Sessions John W. , Hanks Brad W. , Lewis Tyler E. , Jensen Brian D. , Lindstrom Dallin L. , Burnett Sandra H.
Published: January 2015

Being able to deliver molecular loads to the intracellular space of mammalian cells is a key initial step of genetic engineering. In the following work, experimentation with nanoinjection, a non-viral molecular load delivery technique, was examined in regards to transmembrane delivery of propidium iodide (PI), a dye that cannot penetrate the cell membrane and fluoresces when bound to genetic material. Investigation includes two environmental factors: peak pulse amplitude (1.5 to 3, 5, 7, or 9 V) and saline type (HBSS, PBS with potassium, and PBS without potassium). Results indicate that PBS with potassium has significantly higher PI uptake efficiency than the other two saline solutions for pulsed voltages of 3V, 5V, and 7V (with the peak value being 3.352 times greater than the positive control). Also, cell viability analysis indicates that there is a measureable reduction in cell viability for voltage protocol samples in comparison to non-voltage protocol samples. Cell viabilities range from 74.5% to 89.4% for voltage protocol samples. Findings suggest that a possible combination of physical/electrical variables work in concert with biological mechanisms to contribute to overall cell survival and PI uptake efficiency in nanoinjection.
A Network Based Dynamic Model for Product Family Evolution
Authors: Park Kijung , Okudan Kremer Gül E.
Published: January 2015

Products evolve over time to follow new customer needs and technologies. Although the proper estimation of future products has been regarded as a critical issue for business success, it has not been widely discussed in an analytical way. Focusing on the evolution of a product family, this paper aims to develop a dynamic model which can effectively show the structural changes of a product family over time. The proposed model is based on a network representing the structural architecture of a product family. This model employs the concept of Fitness Model [1], where nodes in a certain system have their own fitness values to represent the degree of gaining edges with new nodes. The dynamic model proposed in this paper would be a basis for the estimation of product family evolution; it is potentially effective to simulate possible future structures of a product family according to different platform leveraging strategies.
Analytical Solutions for Period-1 Motions in a Nonlinear Jeffcott Rotor System
Authors: Huang Jianzhe , Luo Albert C. J.
Published: January 2015

In this paper, the analytical solutions of period-1 solutions are developed, and the corresponding stability and bifurcation are also analyzed by eigenvalue analysis. The Hopf bifurcations of periodic motions cause not only the bifurcation tree but quasi-periodic motions. The quasi-periodic motion can be stable or unstable. Displacement orbits of periodic motions in the nonlinear Jeffcott rotor systems are illustrated, and harmonic amplitude spectrums are presented for harmonic effects on periodic motions of the nonlinear rotor.
Robotic Rehabilitation Device and Patient Orientation Estimation
Authors: Homich Andrew J. , Doerzbacher Megan A. , Piazza Stephen J. , Hills Everett C. , Moore Jason Z.
Published: January 2015

This paper explores the design of a robotic device for gait rehabilitation and assessment, as well as a method to estimate a patient’s orientation within the rehabilitation device. Current rehabilitation methods require the patient to propel the assistive device or offer limited walking distance. Additionally, current devices do not measure the patient’s reliance on the assistive device, possibly prolonging the rehabilitation period or even preventing satisfactory function to be regained. A novel robotic parallel bar platform was designed to address the shortfalls of current assistive devices. A complementary filter was developed to estimate the patient’s orientation within the device using a magnetometer and gyroscope. Experiments of the complementary filter on a test platform show that the filter provides estimates within five degrees of the true value over a range of angular velocities.
Period-1 Motions in a Time-Delayed Duffing Oscillitor With Periodic Excitation
Authors: Luo Albert C. J. , Jin Hanxiang
Published: January 2015

In this paper, analytical solutions of period-1 motions in a time-delayed Duffing oscillator with a periodic excitation are investigated through the Fourier series, and the stability and bifurcation of such periodic motions are discussed by eigenvalue analysis. The symmetric and asymmetric period-1 motions in such time-delayed Duffing oscillator are obtained analytically, and the frequency-amplitude characteristics of period-1 motions in such a time-delayed Duffing oscillator are investigated. Numerical illustrations of period-1 motions are given by numerical and analytical solutions.
Kinematic Analysis of the 3-RPS Cube Parallel Manipulator
Authors: Nurahmi Latifah , Schadlbauer Josef , Husty Manfred , Wenger Philippe , Caro Stéphane
Published: January 2015

The 3-RPS Cube parallel manipulator, a three-degree-of-freedom parallel manipulator initially proposed by Huang et al. in 1995, is analysed in this paper with an algebraic approach, namely Study kinematic mapping of the Euclidean group SE(3) and is described by a set of eight constraint equations.

A primary decomposition is computed over the set of eight constraint equations and reveals that the manipulator has only one operation mode. Inside this operation mode, it turns out that the direct kinematics of the manipulator with arbitrary values of design parameters and joint variables, has sixteen solutions in the complex space. A geometric interpretation of the real solutions is given.

The singularity conditions are obtained by deriving the determinant of the Jacobian matrix of the eight constraint equations. All the singular poses are mapped onto the joint space and are geometrically interpreted. By parametrizing the set of constraint equations under the singularity conditions, it is shown that the manipulator is in actuation singularity. The uncontrolled motion gained by the platform is also provided.
Conceptual Design of Lower-Mobility Parallel Manipulators Based on Wrench Graphs
Authors: El-Ghazaly Gamal , Caro Stéphane
Published: January 2015

This paper presents a design methodology for lower-mobility parallel manipulators based on classification of wrench systems into four main classes. Wrench systems are represented in a three-dimensional projective space ℙ3 using wrench graphs where it is easy to incorporate geometric constraints to have simple singularity conditions using Grassmann-Cayley algebra (GCA). The main idea of the approach is to design a PM with an overall (constraint and actuation) wrench system that complies with a given wrench graph for which singularity conditions have been predetermined. The main advantage of this methodology is that the singularity conditions are already known a priori and consequently, it gives an opportunity to avoid such conditions at the design stage and make them unreachable. In the worst case scenario, where none of singularity conditions cannot be avoided, one can have a PM with known singular configurations which are always difficult to determine for already designed manipulators. As illustrative examples, two different five degrees-of-freedom (dof) mechanisms have been designed based on some of the defined wrench graphs giving 3T2R motion pattern. The first mechanism has some avoided singularities and the second one is free of singularity.
The Effects of the Undergraduate Curriculum and Individual Differences on Student Innovation Capabilities
Authors: Kershaw Trina C. , Seepersad Carolyn Conner , Hölttä-Otto Katja , Williams Paul T. , Young Adam P. , Bhowmick Sankha , McCarthy Molly A.
Published: January 2015

Innovation is considered a key to competitiveness of the nation. In order to ensure that graduating students are equipped with innovation skills to meet this challenge, we must ensure that engineering curricula are enhancing students’ innovation capabilities. In this paper we investigate if the undergraduate engineering curriculum can have a significant positive effect on students’ innovation capabilities. In addition, we investigate if individual difference factors, such as engineering design self-efficacy and self-reported GPA, can be correlated with innovation capabilities. To test this, we assessed students’ solutions to specific open ended problems for their level of innovation, or more specifically, originality and technical feasibility. The experiments were replicated at two universities and with a variety of cohorts, including freshman students before and after an introductory engineering course and senior mechanical engineering students before and after a capstone course. We found that that students’ innovation capabilities were enhanced by the senior-level capstone course at both universities. Similar positive results can be found for the overall four year curriculum at both schools. While individual differences in academic performance and engineering design self-efficacy did not predict seniors’ performance, these individual difference factors did interact to influence originality in the freshmen students. At high levels of GPA, increased self-efficacy led to increased originality, but at low levels of GPA, increased self-efficacy led to lower originality scores. Results are discussed in relation to prior research and suggestions are made to track freshmen students to better train future engineers.
Eliminating Boundary Nodes in Substructuring of Large Structures
Authors: Kazemi Omid , Nikravesh Parviz E.
Published: January 2015

Substructuring techniques have been widely used in model reduction of large structures. In these methods a large structure is partitioned into several components and reduced components are built. Boundary degrees-of-freedom (DoF) at the interfaces between components are used to assemble the reduced components and to form a reduced model of the original structure. In the current substructuring methods the boundary DoF or a transformation of these DoF remain in the reduced model. In this paper a methodology is suggested that could eliminate the boundary DoF from the reduced model which in turn leads to having even a smaller reduced model. This method which uses a different partitioning of the DoF of the structure is illustrated for a two-component structure. An example on a simple structure shows how the method can be implemented. The results show that the same level of accuracy compared to a standard substructuring can be obtained with fewer number of DoF in the reduced model.
Comparison Study on Motion Characteristics of Three 2-DOF Pointing Devices
Authors: Wu Kang , Yu Jingjun , Zong Guanghua , Kong Xianwen
Published: January 2015

Two degree-of-freedom (DOF) manipulators have been widely applied in pointing devices. Besides the commonly used gimbal platforms, two different kinds of parallel platforms base on parallel manipulators are presented as real applications in this paper. In a situation, a pointing device acquires and tracks a remote target via optical sensors amounted on the device. As the authors’ recent research, there are image distortions caused by deflected camera axis while the pointing device changing its attitudes. The paper refers the phenomena to the self-motion characteristics as the 2-DOF platforms rotate around the fixed platform axis. Basic image distortion principles of the three platforms are illustrated and discussed. Relationship between the self-motion and revolution are analyzed via the graphic approach and simulated on the software. Results indicate that these different phenomena are due to the different inherent characters of the platform’s freedom lines and freedom disks. Conclusions revealed in this paper would help the engineers with the type selections and applications, especially for the remote virtual reality devices which can provide realistic images for the human eyes. This work will facilitate the image processing and improve the measuring accuracy for the pointing devices.
Development of Sustainable Design Index for Office Furniture Design and its CAD-Based Implementation
Authors: Seyajah N. , Cheng K. , Bateman R.
Published: January 2015

Sustainable design is a universal concern and due to that it becomes significant reference in numerous industries especially furniture products. In order to overcome the difficulties in Furniture Industry to determine the sustainable design to their products, the concept of Sustainable Design Index (SDI) was proposed in this paper. The SDI construction is combined with the designer’s daily activities and the design process, in this research the open plan system (OPS) is used for the subject matter. This paper presents several design tools and strategies which are integrated to support the development of sustainable design index as a solution. It is important to develop a model or method for formulating the SDI for industry to work with particularly the product’s sustainability performance strongly linking to the consumer’s satisfaction. In order to develop a robust SDI representation, an innovative approach for structured and systematic sustainable furniture design is proposed mainly based on modular product architecture, reconfigurability, using design structure matrix (DSM) and axiomatic design (AD). The SDI implementation is to enhance the designer by seamlessly integrating SDI algorithms within the CAD design environment and designers’ design operations.
Graph Based Representation and Analyses for Conceptual Stages
Authors: Coatanéa Eric , Nonsiri Sarayut , Christophe Francois , Mokammel Faisal
Published: January 2015

What is the fundamental similarity between investing in stock of a company, because you like the products of this company, and selecting a design concept, because you have been impressed by the esthetic quality of the presentation made by the team developing the concept?

Except that both decisions are based on a surface analysis of the situations, they both reflect a fundamental human’s cognitive feature. Human brain is profoundly trying to minimize the efforts required to solve a cognitive task and is using when possible an automatic mode relying on recognition, memory, and causality. This mode is even used in some occasion without the engineer being conscious of it. Such type of tendencies are naturally pushing engineers to rush into known solutions, to avoid analyzing the context of a design problem, to avoid modelling design problems and to take decision based on isolated evidences. Those behaviors are familiar to experience teachers and engineers. This tendency is magnified by the time pressure imposed to the engineering design process. Early phases in particular have to be kept short despite the large impact of decisions taken at this stage. Few support tools are capable of supporting a deep analysis of the early design conditions and problems regarding the fuzziness and complexity of the early stage. The present article is hypothesizing that the natural ability of humans to deal with cause-effects relations push toward the massive usage of causal graphs analysis during the design process and specifically during the early phases. A global framework based on graphs is presented in this paper to efficiently support the early stages. The approach used to generate graphs, to analyze them and to support creativity based on the analysis is forming the central contribution of this paper.
Eigenvalue Veering in Quartz Tuning Fork Sensors and its Effect on Dynamic Atomic Force Microscopy
Authors: Melcher John
Published: January 2015

Quartz tuning fork (QTF) sensors offer an attractive alternative to traditional silicon microcantilevers for sensing applications in dynamic atomic force microscopy (DAFM). The QTF sensor consists of two identical, weakly-coupled tines with a sharp tip affixed to the distal end of one tine. The fundamental anti-phase mode of the QTF achieves a stable resonant frequency with a high Quality factor making it ideal for DAFM applications in which a small shift in the resonant frequency is linked to a tip-sample force. The addition of the tip-sample force also breaks the symmetry of the QTF leading to a classic eigenvalue veering scenario. The eigenvalue veering and accompanying mode localization phenomena violate the standard DAFM modeling assumptions which treat the addition of the tip-sample force as a small perturbation to a single-degree-of-freedom oscillator. We find that the eigenvalue veering can contribute a systematic error in force measurements on the order of 20%. Methodology for correcting the systematic error caused by eigenvalue veering is proposed.
Fast Virtual Stenting With Vessel-Specific Initialization and Collision Detection
Authors: Paliwal Nikhil , Yu Hongyu , Damiano Robert , Xiang Jianping , Yang Xinjian , Siddiqui Adnan , Li Haiyun , Meng Hui
Published: January 2015

Recent studies show that placement of neurovascular stents during treatment procedure plays a vital role in modifying the hemodynamics in aneurysm sac and parent vessel. This study proposes an improved fast virtual stenting method for stent deployment, which can be used in treatment planning by comparing different treatment strategies. This method is built upon the FVS[1] method by Larrabide et al., which expands the stent within blood vessel by providing artificial mathematical forces. Current method incorporates two innovations: an improved initialization of the stent and an advanced collision detection method between parent vessel and stent to prevent stent from going out of the vessel. These improvements enable this method to deploy stents within time comparable to clinical surgical procedure and help clinicians in quick decision-making during treatment strategy.
Computational Hemodynamic Evaluation of Two Clinical Flow-Diverter Treatment Strategies: Overlapping Stents vs. Dense Compaction of a Single Stent
Authors: Damiano Robert , Xiang Jianping , Siddiqui Adnan , Meng Hui
Published: January 2015

We employed computational fluid dynamics (CFD) and finite element method (FEM) to investigate the hemodynamic effect of two flow-diversion strategies of cerebral aneurysm treatment: overlapping stents and dense compaction of a single stent. Three representative patient-specific aneurysms were used as test cases, and flow diverters were virtually deployed into the models. Aneurysmal hemodynamic modification by flow diverters is strongly correlated with the metal coverage rate across the aneurysm neck, and not uniquely determined by FD deployment strategies. Fusiform aneurysms may be more favorable for achieving dense compaction for increased metal coverage rate than saccuclar aneurysms. To induce high flow reduction, the overlapping strategy may be more suitable for sidewall aneurysms, and the dense compaction strategy for fusiform aneurysms.
The mitotic checkpoint protein kinase BUB1 is an engine in the TGF-β signaling apparatus
Authors: Moustakas Aristidis
Published: January 2015

Potential crosstalk between TGF-β signaling and the mitotic checkpoint opens new avenues for research.
Getting Specific About Amino Acid Sensing
Authors: Ray L. Bryan
Published: January 2015

Distinct mechanisms sense amino acids leucine and glutamine at the lysosome.
MyD88-Dependent Signaling Drives Host Survival and Early Cytokine Production during Histoplasma capsulatum Infection
Authors: Coady Alison , Sil Anita
Published: January 2015

The ability of the innate immune system to trigger an adaptive T cell response is critical to resolution of infection with the fungal pathogenHistoplasma capsulatum. However, the signaling pathways and cell types involved in the recognition of and response to this respiratory pathogen remain poorly defined. Here, we show that MyD88, an adaptor protein vital to multiple innate immune pathways, is critically required for the host response toHistoplasma. MyD88-deficient (MyD88−/−) mice are unable to control the fungal burden and are more sensitive toHistoplasmainfection than wild-type, Dectin-1−/−, or interleukin 1 receptor-deficient (IL-1R−/−) mice. We found that MyD88 is necessary for the production of key early inflammatory cytokines and the subsequent recruitment of inflammatory monocytes to the lung. In both ourin vitroandex vivoanalyses, MyD88 was intrinsically required in dendritic cells and alveolar macrophages for initial cytokine production. Additionally, MyD88-deficient bone marrow-derived dendritic cells fail to efficiently control fungal growth when cocultured with primed splenic T cells. Surprisingly, mice that lack MyD88 only in dendritic cells and alveolar macrophages are competent for early cytokine production and normal survival, indicating the presence of compensatory and redundant MyD88 signaling in other cell types during infection. Ultimately, global MyD88 deficiency prevents proper T cell activation and gamma interferon (IFN-γ) production, which are critical for infection resolution. Collectively, this work reveals a central role for MyD88 in coordinating the innate and adaptive immune responses to infection with this ubiquitous fungal pathogen of humans.
Small-Molecule Inhibitors of Gram-Negative Lipoprotein Trafficking Discovered by Phenotypic Screening
Authors: McLeod Sarah M. , Fleming Paul R. , MacCormack Kathleen , McLaughlin Robert E. , Whiteaker James D. , Narita Shin-ichiro , Mori Makiko , Tokuda Hajime , Miller Alita A.
Published: January 2015

In Gram-negative bacteria, lipoproteins are transported to the outer membrane by the Lol system. In this process, lipoproteins are released from the inner membrane by the ABC transporter LolCDE and passed to LolA, a diffusible periplasmic molecular chaperone. Lipoproteins are then transferred to the outer membrane receptor protein, LolB, for insertion in the outer membrane. Here we describe the discovery and characterization of novel pyridineimidazole compounds that inhibit this process.
Escherichia coli
mutants resistant to the pyridineimidazoles show no cross-resistance to other classes of antibiotics and map to either the LolC or LolE protein of the LolCDE transporter complex. The pyridineimidazoles were shown to inhibit the LolA-dependent release of the lipoprotein Lpp from
E. coli
spheroplasts. These results combined with bacterial cytological profiling are consistent with LolCDE-mediated disruption of lipoprotein targeting to the outer membrane as the mode of action of these pyridineimidazoles. The pyridineimidazoles are the first reported inhibitors of the LolCDE complex, a target which has never been exploited for therapeutic intervention. These compounds open the door to further interrogation of the outer membrane lipoprotein transport pathway as a target for antimicrobial therapy.
The Formation of Streptococcus mutans Persisters Induced by the Quorum-Sensing Peptide Pheromone Is Affected by the LexA Regulator
Authors: Leung Vincent , Ajdic Dragana , Koyanagi Stephanie , Lévesque Céline M.
Published: January 2015

The presence of multidrug-tolerant persister cells within microbial populations has been implicated in the resiliency of bacterial survival against antibiotic treatments and is a major contributing factor in chronic infections. The mechanisms by which these phenotypic variants are formed have been linked to stress response pathways in various bacterial species, but many of these mechanisms remain unclear. We have previously shown that in the cariogenic organism
Streptococcus mutans
, the quorum-sensing peptide CSP (competence-stimulating peptide) pheromone was a stress-inducible alarmone that triggered an increased formation of multidrug-tolerant persisters. In this study, we characterized SMU.2027, a CSP-inducible gene encoding a LexA ortholog. We showed that in addition to exogenous CSP exposure, stressors, including heat shock, oxidative stress, and ofloxacin antibiotic, were capable of triggering expression of
lexA
in an autoregulatory manner akin to that of LexA-like transcriptional regulators. We demonstrated the role of LexA and its importance in regulating tolerance toward DNA damage in a noncanonical SOS mechanism. We showed its involvement and regulatory role in the formation of persisters induced by the CSP-ComDE quorum-sensing regulatory system. We further identified key genes involved in sugar and amino acid metabolism, the clustered regularly interspaced short palindromic repeat (CRISPR) system, and autolysin from transcriptomic analyses that contribute to the formation of quorum-sensing-induced persister cells.
Mutations within the
mepA
Operator Affect Binding of the MepR Regulatory Protein and Its Induction by MepA Substrates in Staphylococcus aureus
Authors: Schindler Bryan D. , Seo Susan M. , Birukou Ivan , Brennan Richard G. , Kaatz Glenn W.
Published: January 2015

The expression of
mepA
, encoding the
Staphylococcus aureus
MepA multidrug efflux protein, is repressed by the MarR homologue MepR. Repression occurs through binding of two MepR dimers to an operator with two homologous and closely approximated pseudopalindromic binding sites (site 1 [S1] and site 2 [S2]). MepR binding is impeded in the presence of pentamidine, a MepA substrate. The effects of various
mepA
operator mutations on MepR binding were determined using electrophoretic mobility shift assays and isothermal titration calorimetry, and an
in vivo
confirmation of the effects observed was established for a fully palindromic operator mutant. Altering the S1-S2 spacing by 1 to 4 bp severely impaired S2 binding, likely due to a physical collision between adjacent MepR dimers. Extension of the spacing to 9 bp eliminated the S1 binding-mediated DNA allostery required for efficient S2 binding, consistent with positive cooperative binding of MepR dimers. Binding of a single dimer to S1 was maintained when S2 was disrupted, whereas disruption of S1 eliminated any significant binding to S2, also consistent with positive cooperativity. Palindromization of binding sites, especially S2, enhanced MepR affinity for the
mepA
operator and reduced MepA substrate-mediated MepR induction. As a result, the on-off equilibrium between MepR and its binding sites was shifted toward the on state, resulting in less free MepR being available for interaction with inducing ligand. The selective pressure(s) under which
mepA
expression is advantageous likely contributed to the accumulation of mutations in the
mepA
operator, resulting in the current sequence from which MepR is readily induced by MepA substrates.
A predictive model of hospitalization cost after cerebral aneurysm clipping
Authors: Bekelis Kimon , Missios Symeon , MacKenzie Todd A , Labropoulos Nicos , Roberts David W
Published: January 2015

Background

Cost containment is the cornerstone of the Affordable Care Act. Although studies have compared the cost of cerebral aneurysm clipping (CAC) and coiling, they have not focused on identification of drivers of cost after CAC, or prediction of its magnitude. The objective of the present study was to develop and validate a predictive model of hospitalization cost after CAC.

Methods

We performed a retrospective study involving CAC patients who were registered in the Nationwide Inpatient Sample (NIS) database from 2005 to 2010. The two cohorts of ruptured and unruptured aneurysms underwent 1:1 randomization to create derivation and validation subsamples. Regression techniques were used for the creation of a parsimonious predictive model.

Results

Of the 7798 patients undergoing CAC, 4505 (58%) presented with unruptured and 3293 (42%) with ruptured aneurysms. Median hospitalization cost was US$24 398 (IQR $17 079 to $38 249) and $73 694 (IQR $46 270 to $115 128) for the two cohorts, respectively. Common drivers of cost identified in the multivariate analyses included the following: length of stay, number of admission diagnoses and procedures, hospital size and region, and patient income. The models were validated in independent cohorts and demonstrated final R2values very similar to the initial models. The predicted and observed values in the validation cohort demonstrated good correlation.

Conclusions

This national study identified significant drivers of hospitalization cost after CAC. The presented model can be utilized as an adjunct in the cost containment debate and the creation of data driven policies.
Effect of a VietnameseCinnamomum cassiaessential oil and its major componenttrans-cinnamaldehyde on the cell viability, membrane integrity, membrane fluidity, and proton motive force ofListeria innocua
Authors: Trinh Nga-Thi-Thanh , Dumas Emilie , Thanh Mai Le , Degraeve Pascal , Amara Chedia Ben , Gharsallaoui Adem , Oulahal Nadia
Published: January 2015

The antibacterial mechanism of a Cinnamomum cassia essential oil from Vietnam and of its main component (trans-cinnamaldehyde, 90% (m/m) of C. cassia essential oil) against a Listeria innocua strain was investigated to estimate their potential for food preservation. In the presence of C. cassia essential oil or trans-cinnamaldehyde at their minimal bactericidal concentration (2700 μg·mL–1), L. innocua cells fluoresced green after staining with Syto9® and propidium iodide, as observed by epifluorescence microscopy, suggesting that the perturbation of membrane did not cause large pore formation and cell lysis but may have introduced the presence of viable but nonculturable bacteria. Moreover, the fluidity, potential, and intracellular pH of the cytoplasmic membrane were perturbed in the presence of the essential oil or trans-cinnamaldehyde. However, these membrane perturbations were less severe in the presence of trans-cinnamaldehyde than in the presence of multicomponent C. cassia essential oil. This indicates that in addition to trans-cinnamaldehyde, other minor C. cassia essential oil components play a major role in its antibacterial activity against L. innocua cells.
Stability analysis for discrete-time neural networks with time-varying delays and stochastic parameter uncertainties
Authors: Kwon O.M. , Park M.J. , Lee S.M. , Cha E.J.
Published: January 2015

This paper proposes new delay-dependent stability criteria for discrete-time neural networks with interval time-varying delays and probabilistic occurring parameter uncertainties. It is assumed that parameter uncertainties are changed with the environment, explored using random situations, and its stochastic information is included in the proposed method. By constructing a suitable Lyapunov–Krasovskii functional, new delay-dependent stability criteria for the concerned systems are established in terms of linear matrix inequalities, which can be easily solved by various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed method.
Higher derivative corrections of f(R) gravity with varying equation of state in the case of variable G and Λ
Authors: Khurshudyan M. , Pourhassan B. , Pasqua A.
Published: January 2015

In this paper, we study three models of f(R) modified gravity including higher order terms based on different equation of state parameters. We also assume variable G and Λ. Using numerical analysis, we obtain the behavior of some important cosmological parameters, like the Hubble expansion H parameter and the deceleration parameter q. Statefinder diagnostics are also performed for all models.
Thomas–Wigner rotation and Thomas precession in covariant ether theories: novel approach to experimental verification of special relativity
Authors: Kholmetskii Alexander L. , Yarman Tolga
Published: January 2015

We continue the analysis of Thomas–Wigner rotation (TWR) and Thomas precession (TP) initiated in (Kholmetskii and Yarman. Can. J. Phys. 92, 1232 (2014). doi:10.1139/cjp-2014-0015 ; Kholmetskii et al. Can. J. Phys. 92, 1380 (2014). doi:10.1139/cjp-2014-0140 ), where a number of points of serious inconsistency have been found in the relativistic explanation of these effects. These findings motivated us to address covariant ether theories (CET), as suggested by the first author (Kholmetskii. Phys. Scr. 67, 381 (2003)) and to show that both TWR and TP find a perfect explanation in CET. We briefly reproduce the main points of CET, which are constructed on the basis of general symmetries of empty space–time, general relativity principles, and classical causality, instead of Einstein’s postulates of the special theory of relativity (STR). We demonstrate that with respect to all known relativistic experiments performed to date in all areas of physics, both theories, STR and CET, yield identical results. We further show that the only effect that differentiates STR and CET is the measurement of time-dependent TWR of two inertial frames, K1 and K2, related by the rotation-free Lorentz transformation with a third inertial frame, K0, in the situation, where the relative velocity between K1 and K2 remains fixed. We discuss the results obtained and suggest a novel experiment, which can be classified as a new crucial test of STR.
Reply to the comment by Harron on “Widespread declines in woodland caribou (Rangifer tarandus caribou) continue in Alberta”
Authors: Hervieux D. , Hebblewhite M. , DeCesare N.J. , Russell M. , Smith K. , Robertson S. , Boutin S.
Published: January 2015

Estimation of demographic trends from vital rates provides a powerful means to estimate population trends in cryptic or difficult to study species such as woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). Using such methods, Hervieux et al. (2013; Can. J. Zool. 91(12): 872–882) recently showed 11 of 14 woodland caribou populations in Alberta were declining at ∼8%/year following up to 18 years of monitoring. Harron (2015; Can. J. Zool. 93(2): 149–150) critiques our original study, claiming that negative biases in our demographic monitoring exaggerate our conclusions of widespread caribou declines. Here, we systematically review each of Harron’s claims of bias, rejecting each of his claims upon careful review of the mechanisms by which his purported claims would manifest in our population trend estimation. Therefore, we conclude that Harron’s scientific critique was superficial and misleading. Delays in conservation actions raised by Harron’s critique risk diminishing opportunities to conserve and recover this federally and provincially protected species.