bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Reconfiguration for Performance Enhancement in Articulated Wheeled Vehicles
Authors: Alamdari Aliakbar , Krovi Venkat
Published: December 2014

Leg-wheel architectures for locomotion systems offer many advantages, not the least of which is reconfigurability of wheel-axle with respect to the chassis. Thus, locomotion systems with multiple leg-wheels now permit enormous reconfigurability of the chassis frame with respect to the ground frame. We seek to systematically exploit this ability to reconfigure within this highly-redundant system to enhance contact kinematics i.e., reducing the slippage and improving traction forces at wheel-ground interfaces. In addition, reconfiguration can also be used to mitigate undesirable system-level effects (such as judder) and lead to greatly improved estimation for navigation. In this paper, we examine a systematic analytical approach to the modeling, analysis and reconfiguration of articulated leg-wheel systems, to enhance both traction as well as stability-margin, while navigating over rough-terrains. The derivations will also be specialized to a particular example of an ultra-mobile actively-articulated vehicle to illustrate the developed procedure.
A General Power Modeling Framework for Individual Building Demand Management
Authors: Touretzky Cara R. , Patil Rakesh
Published: December 2014

The class of buildings designated as commercial is comprised of many different architectures and functions, which presents a challenge when developing demand management strategies that are applicable across this field. Most advanced controllers are based on a model of the thermal loads in the building envelope. These models do not directly extrapolate to measures of power consumption, which is what building owners are ultimately interested in managing. In this work, we develop models of power use that can be easily tailored to model power demand in any commercial building with advanced sensing and metering. We address how existing models of the building temperature states can be incorporated into our framework. Specifically, we show how Auto-Regressive models with eXogeneous (ARX) inputs can be used for superior day-ahead forecasting of demand, and how to formulate the models in a way that is meaningful at the supervisory level. These models provide more flexibility in the design of a supervisory controller for building energy management and the information they provide is crucial for bridging the gap between buildings and utilities in the smart grid.
Modeling and Analysis of a CNG Residential Refueling System
Authors: Bang Hyo Joon , Stockar Stephanie , Muratori Matteo , Rizzoni Giorgio
Published: December 2014

Natural gas has recently been proposed as an alternative fuel for transportation in the United States. Refueling infrastructure is the major technological barrier to the market penetration of passenger compressed natural gas (CNG) vehicles. Currently, there is about one natural gas refueling station every 150 gasoline pumps. Nevertheless, natural gas is widely available in American houses, and thus distributed residential refueling is seen as a viable solution.

Generally, residential CNG refueling systems use compressors driven by electric motors. With a potential increase in the number of residential natural gas refueling systems over the next few years, the additional load that this system will introduce on the electric power infrastructure can be significant. In this paper, a system dynamic model of a residential refueling system has been developed and validated against data available in the literature. Ultimately, the model will allow for exploring the impact of residential refueling of CNG vehicles on the electric power infrastructure.
An Intelligent Pumping System to Cope With Gas Volume Fraction of the Oil-Well Multi-Phase Flow
Authors: Hashemi Ali , Omrani Ala E. , Franchek Matthew A. , Grigoriadis Karolos , Ebrahimi Behrouz
Published: December 2014

A novel approach is presented to model the interplay between the gas volume fraction (GVF) and the driving force of the pumping unit. A physics-based model is proposed to predict the down-hole pressure for a constant, but unknown GVF and given oil flow-rate out of the well. The identified down-hole pressure is used to model the saddle-bearings axial displacements, which are indicative of polished-rod loading. The imbalance between the data obtained from the detailed model of the pumping unit, and predicted bearing’s displacements can be employed then to estimate the value of the GVF. The resulted GVF is incorporated into the sucker-rod string dynamics to determine the natural frequency of the system. A control strategy is then used to adjust the pump speed to compensate for the GVF variations while avoiding the resonance frequency of the sucker-rod string. A low dimensional simulation is performed and the results are demonstrated for upstroke movement of the sucker-rod.
Pony II Robot: Inertially Actuated Baton With Double-Action Pendulums
Authors: Zoghzoghy Joe , Hurmuzlu Yilrdirim
Published: December 2014

In this paper, we present a robotic locomotor with inertia-based actuation. The goal of this system is to generate various gait modes of a baton, consisting of two masses connected with a massless rod. First, a model for a baton prototype called Pony II is presented. This model incorporates the double-action inertial actuation generated by two rotating pendulums, spinning at constant angular velocities in opposite directions. This system allows regulation of the inertial forces generated by the spinning masses. In addition, it provides control over the orientation of the resultant inertial force. Numerical simulations of four stable gaits are presented: dragging, tapping, galloping, and hopping. We also developed an experimental prototype, called Pony II, consisting of the double-action actuators. The robot successfully generates all the simulated gaits. In addition, we show that the robot is capable of generating progression on low friction surfaces.
Dissipation-Induced Self-Recovery in Systems on Principal Bundles
Authors: Dear Tony , Kelly Scott David , Travers Matthew , Choset Howie
Published: December 2014

The “self-recovery” phenomenon is a seemingly curious property of certain underactuated dissipative systems in which dissipative forces always push the system to a pre-determined equilibrium state dependent on the initial conditions. The systems for which this has been studied are Abelian, with all system velocity interactions due entirely to inertial effects. In this paper we also consider Abelian systems, but in the context of principal bundles, and introduce drag in addition to inertial interactions, allowing us to show that the same conservation that induces self-recovery now depends on the trajectories of the system inputs in addition to initial conditions. We conclude by demonstrating an example illustrating the conditions derived from our proof, along with an observation that the present analysis is insufficient for self-recovery in non-Abelian systems.
A Hysteresis-Compensated Self-Sensing Scheme for Vanadium Dioxide-Coated Microactuators
Authors: Zhang Jun , Torres David , Merced Emmanuelle , Sepúlveda Nelson , Tan Xiaobo
Published: December 2014

Vanadium dioxide (VO2)-coated silicon dioxide microactuators demonstrate fully reversible actuation, large bending and high energy density. To better utilize its actuation potential while minimizing the cost in obtaining sensory feedback, a novel composite hysteresis model is presented to obtain the deflection feedback based on the resistance measurement. In this model the deflection is obtained from the voltage value through a generalized Prandtl-Ishlinskii model, while the voltage in turn is calculated based on the resistance measurement through the analytical inverse of another generalized Prandtl-Ishlinskii model. For comparison purposes, a Preisach model and a polynomial model, respectively, are adopted to estimate the deflection based on resistance measurement directly. Experimental results show that, for a 550 μm long VO2-based microactuator, the average absolute errors of the self-sensing schemes based on the composite model, the Preisach model, and the polynomial model are 0.554 μm, 1.232 μm, and 2.898 μm, respectively, over the deflection range of [−0.2, 102.9] μm. The composite model also shows advantages over the Preisach model in terms of the calculation time needed in deflection estimation. In addition, in separate verification experiments, the error resulted from the composite model-based self-sensing scheme is only 60% and 40 % of those under the schemes using the Preisach model and the polynomial model, respectively.
Nonuniform Coverage With Time-Varying Diffusive Density
Authors: Miah Suruz , Nguyen Bao , Bourque Alex , Spinello Davide
Published: December 2014

We address nonuniform coverage with networked multi-agent systems and a nonuniform, time varying risk density function throughout the spatial workspace. The proposed solution for the nonuniform coverage problem is different from existing ones in that the evolution of the density is described by a conservation law with time-varying boundary conditions. By adopting a first gradient constitutive relation between the flux and the density we obtain a simple diffusion equation. The diffused density is then employed by a platoon of autonomous agents for spatially configuring themselves in optimum locations so that the coverage metric is maximized or minimized. We exploit the generalized centroidal Voronoi tessellation technique for generating the motion control of autonomous agents. By assuming that the risk density evolves much faster than the boundary conditions, we prove that the generalized Voronoi centroids are equilibrium points for the coverage metric. A set of numerical simulations illustrate the theoretical results.
A Sensitivity Based Iterative Approach for Tuning Damper Parameters in Combination With the Controller to Increase Closed Loop Performance
Authors: Verbaan C. A. M. , Rosielle P. C. J. N. , Steinbuch M.
Published: December 2014

In motion systems, high controller gains are beneficial in order to suppress disturbances acting on the system. Low-damped non-rigid body (NRB) resonances usually limit this controller gain. The result is a bound on the maximum achievable sensitivity, i.e. the suppression of low frequent position disturbances. Robust Mass Dampers (RMD’s) with a relatively high damping value have shown to be able to increase the NRB damping over a broad frequency range. The main difficulty is to determine the stiffness and damping parameters for these damper mechanisms in order to optimize the closed loop performance of the motion system. This paper proposes a modulus margin based iterative optimization procedure which includes a plant model with dampers added and a PID+ type controller. The results are optimal damper parameters — stiffness and damping — in combination with an as high as possible controller gain, which result in an improved disturbance suppression at frequencies below the bandwidth and a faster setpoint tracking.
Maximizing Parameter Identifiability of an Equivalent-Circuit Battery Model Using Optimal Periodic Input Shaping
Authors: Rothenberger Michael J. , Anstrom Joel , Brennan Sean , Fathy Hosam K.
Published: December 2014

This paper shapes the periodic cycling of a lithium-ion battery to maximize the battery’s parameter identifiability. The paper is motivated by the need for faster and more accurate lithium-ion battery diagnostics, especially for transportation. Poor battery parameter identifiability makes diagnostics challenging. The existing literature addresses this challenge by using Fisher information to quantify battery parameter identifiability, and showing that test trajectory optimization can improve identifiability. One limitation is this literature’s focus on offline estimation of battery model parameters from multi-cell laboratory cycling tests. This paper is motivated, in contrast, by online health estimation for a target battery or cell. The paper examines this “targeted estimation” problem for both linear and nonlinear second-order equivalent-circuit battery models. The simplicity of these models leads to analytic optimal solutions in the linear case, providing insights to guide the setup of the optimization problem for the nonlinear case. Parameter estimation accuracy improves significantly as a result of this optimization. The paper demonstrates this improvement for multiple electrified vehicle configurations.
Pointwise Angle Minimization: A Method for Guiding Wheeled Robots Based on Constrained Directions
Authors: Soltani-Zarrin Rana , Zeiaee Amin , Jayasuriya Suhada
Published: December 2014

In this paper we consider the point-to-point steering of a two wheeled differential drive mobile robot subject to constrained control inputs where the robot is expected to follow a given path between initial and final points. Formulation of this steering task as a constrained optimal control problem leads to nonlinear two-point boundary value problems. To avoid dealing with boundary value problems while alleviating the complications in analysis of systems with holonomic/non-holonomic constraints, we tackle the problem from a different perspective. This paper proposes a general framework for guiding wheeled robots using constrained direction method. The proposed scheme is equipped with pointwise angle minimization, a search algorithm useful in devising control strategies for steering problems. In addition to computational efficiency, one of the main advantages of the proposed scheme is that it does not impose any restrictive assumptions on the robot’s model. In this paper, kinematics of the robot under the assumption of rolling without slipping has been used as the model of the system and the efficiency of the proposed navigation scheme is illustrated through simulation results. However, the proposed scheme can be applied to more complicated models representing the two wheeled differential robots such as dynamics under slip occurrence.
Enhanced Design of Microgripper Using Double Actuators of Shape Memory Alloy Wires
Authors: Khasawneh Qais , Jaradat Mohammad A. , Alshorman Ahmad
Published: December 2014

In this paper, new design of micro-gripper with shape memory alloy (SMA) actuator is presented. Double SMA actuators were used to enhance the performance of the micro-gripper by using hinge mechanisms; the little displacement of the SMA wire is converted into larger displacement of the tips of the micro-gripper. Stainless steel (St 304) was used as a main material of the gripper structure. Shape memory alloy (Ni-Ti) wires were used as actuators. Finite element model analysis (FEA) using ANSYS software package was used to simulate displacement and stress analysis on the micro gripper. Finally a comparison between the enhanced design and the initial one showed better results in terms of increasing the gripper stroke and reducing the stress on the gripper joints.
Dynamic Weight-Shifting to Reduce Rollover Risk in High Speed Mobile Manipulators
Authors: Storms Justin G. , Tilbury Dawn M.
Published: December 2014

Small unmanned ground vehicles risk rollover at high speeds. This paper proposes use of a manipulator arm on the robot in a dynamic weight-shifting arrangement to reduce rollover risk. A simple linear control law for dynamic weight-shifting of the manipulator arm is proposed. A linear dynamic model is used to analyze the effect of the arm design (link length, mass, etc.) on the roll dynamics, and a more complex nonlinear simulation in Simulink SimMechanics is used to evaluate roll reduction for various steering angles and velocities. Simulations given the same steering input with dynamic weight-shifting showed a roll reduction factor of 12%. For the same radius turn, a roll reduction factor of 29% was observed. A 50% reduction in steering angle was used to achieve a similar turning radius with dynamic weight-shifting activated. By increasing rollover stability, dynamic weight-shifting has the potential to increase safe operating speeds for mobile robots.
Modeling Web Tension Dynamics Considering Thermal and Viscoelastic Effects: Simulations and Experiments
Authors: Jabbar Kadhim A. , Pagilla Prabhakar R.
Published: December 2014

In this paper, a governing equation for web tension considering thermal and viscoelastic effects in a multi-span system is developed. The thermal effect is included in the web tension dynamics by considering the thermal strain induced by temperature distribution in the web span. The viscoelastic effect is introduced by using a standard linear solid (SLS) model from which a relationship between the applied stress and the resulting strain is obtained. Elevated temperature creep and stress relaxation experiments are conducted on several web materials used in an industrial web processing line to determine the viscoelastic parameters of the utilized viscoelastic model. Model simulations are conducted with the same control systems as those used in an industrial web processing line. Data from model simulations are compared with measured data obtained from the industrial web processing line.
Geartrain Reduction for Real-Time Simulation of a Multibody Wind Turbine Gearbox Model
Authors: Schkoda Ryan
Published: December 2014

This paper presents a reduction strategy for a multibody model of a 7.5 MW gearbox located at Clemson University’s Wind Turbine Drivetrain Testing Facility in North Charleston, SC. A model reduction is needed because of a high frequency dynamic associated with the input shaft of the gearbox which prevents the model from being executed in real-time. This particular gearbox has an atypical input stage configuration whereby the load path is split into two parallel shafts before being recombined at the sun shaft. The strategy includes removing model elements associated with high frequency vibration, merging model elements, and locating model elements where needed. The presented strategy successfully removes the problematic eigenvalues, maintains basic dynamic character, and results in a multibody gearbox model suitable for real-time simulation.
Design of Delay Independent State Feedback Control for Roll-to-Roll Printing Applications
Authors: Seshadri Aravind , Pagilla Prabhakar R.
Published: December 2014

Control of print quality (registration) in roll-to-roll (R2R) printing is challenging because of the presence of transport delays involved in the printing process. In this work we present a delay-independent state feedback control design to stabilize a R2R printing press by considering all the significant dynamics involved in the printing process. State feedback control design using past state measurements (controllers with memory) are discussed first. Since controllers with memory are less desirable in industrial applications, we investigate and discuss the feasibility of designing a simple, memoryless, delay-independent state feedback controller for printing applications. The feasibility is shown by the use of a control design procedure that exploits the structure information in the system matrix to find a stabilizing controller. The design procedure is also extended to other common industrial R2R control strategies, such as decentralized control and state feedback with integral action for R2R printing applications.
Qualitative Behavioral Analyzer for Fault Detection and Cyber Security of Control Networks
Authors: Pothuwila Kalana , Berg Jordan M.
Published: December 2014

Cybersecurity for networked industrial control systems presents challenges not faced in information technology systems. The use of heritage protocols, such as Modbus, on unrouted serial buses makes it difficult to authenticate actuator commands and sensor data. Furthermore, rigid master/slave architectures such as Modbus are especially vulnerable to compromise of the master unit. We describe a logic program called the Qualitative Behavioral Analyzer (QBA) for monitoring a controlled physical process on an unrouted Modbus network. The proposed approach uses knowledge of process physics to identify a possible component fault or cyberattack. To avoid relying on the integrity of the master unit, the QBA directly analyzes Modbus network traffic. The first stage of the QBA is called the Network Analyzer, which evaluates each Modbus packet and extract qualitative information. The second stage is called the Physics Analyzer, which evaluates a qualitative physics model based on qualitative information from Network Analyzer. The QBA is demonstrated on simulations of a water treatment process.
Controlling the tunnel resistance of suspended Ni nanogaps using field-emission-induced electromigration
Authors: Toyonaka Takahiro , Morihara Kohei , Takikawa Kazuki , Ito Mitsuki , Shirakashi Jun-ichi
Published: December 2014

The authors report on the ability to control the tunnel resistance of suspended Ni nanogaps by field-emission-induced electromigration. This method is called “activation.” Suspended Ni nanogaps are ideal for investigating activation because the leakage currents flowing through the substrates are suppressed in these structures. The tips of suspended Ni nanogap electrodes are isolated from the SiO2 substrates, so it is expected that the suspended Ni nanogaps act as isolated tunnel junctions during activation. After undergoing activation, the suspended Ni nanogaps clearly exhibited tunneling I–V properties. Furthermore, the authors were able to tune the tunnel resistance of the suspended Ni nanogaps using the activation method. When the applied voltage was swept, the device current switched between high- and low-resistance states. The results imply that activation is a viable method for modulating the electrical properties of suspended Ni nanogaps at the nanometer scale.
Giant current density via indirect exciton orbit overlapping in polarized nanogranular materials
Authors: Koops Hans W. P. , Fukuda Hiroshi
Published: December 2014

Anomalous charge transport in nanogranular material (NGM), closely packed 2–4 nm diameter metal nanoparticle-carbon matrix composite, is modeled using a cluster of electron–hole pairs (super-atom) or indirect excitons produced among locally polarized composite. The observed conductivity and T−1/2 temperature dependence of its logarithm suggests variable range hopping or cotunneling via overlapping orbits among adjacent particles limited by electron–hole interaction. Further, electron–hole liquid is expected from predicted high densities of charge carriers, allowing a giant current carrying capacity. The Bose–Hubbard phase diagram and an interexciton distance shorter than the thermal de Broglie wavelength suggests the possibility of NGM as a platform for excitonic quantum condensate.
Statistical dispersion of nanocomposite emission parameters
Authors: Kolosko Anatoly G. , Popov Eugeni O. , Filippov Sergey V. , Romanov Pavel A.
Published: December 2014

A method for studying fluctuations in the microscopic emission parameters of flat multiple-point cathodes has been developed. For field emitters based on polymer/multiwalled carbon nanotube nanocomposites, the statistical distribution of the effective heights of emission centers has been obtained. Numerical estimates made using Pearson's chi-squared test confirmed that this distribution is lognormal. For these field emitters, the influence of the emission current on the statistical parameters that describe the emission characteristics is discussed.
Comparison of Ar+ Monoatomic and Cluster Ion Sputtering of Ta2O5 at Different Ion Energies, by XPS: Part 1 - Monoatomic Ions
Authors: Grilli Rossana , Simpson Robin , Mallinson Christopher F. , Baker Mark A.
Published: December 2014

A standard 30 nm thick Ta2O5 oxide layer grown on Ta was examined by XPS after Ar+ ion bombardment at ion energies of 200 eV, 500 eV, and 3 keV. The reduction of Ta2O5, resulting from the preferential sputtering of oxygen after ion beam bombardment at different energies has been investigated. Survey spectra, C 1s, Ta 4f and O 1s spectra are presented for each profile at three stages: native surface, after reaching the steady-state oxide composition, and from the underlying metal substrate. Reducing the Ar+ energy from 3 keV to 200 eV makes no substantial difference in the degree of Ta2O5 reduction observed following ion bombardment.
Monitoring ABC‐assisted deep inspiration breath hold for left‐sided breast radiotherapy with an optical tracking system
Authors: Mittauer Kathryn E. , Deraniyagala Rohan , Li Jonathan G. , Lu Bo , Liu Chihray , Samant Sanjiv S. , Lightsey Judith L. , Yan Guanghua
Published: December 2014

Purpose:

Recent knowledge on the effects of cardiac toxicity warrants greater precision for left‐sided breast radiotherapy. Different breath‐hold (BH) maneuvers (abdominal vs thoracic breathing) can lead to chest wall positional variations, even though the patient's tidal volume remains consistent. This study aims to investigate the feasibility of using optical tracking for real‐time quality control of active breathing coordinator (ABC)‐assisted deep inspiration BH (DIBH).

Methods:

An in‐house optical tracking system (OTS) was used to monitor ABC‐assisted DIBH. The stability and localization accuracy of the OTS were assessed with a ball‐bearing phantom. Seven patients with left‐sided breast cancer were included. A free‐breathing (FB) computed tomography (CT) scan and an ABC‐assisted BH CT scan were acquired for each patient. The OTS tracked an infrared (IR) marker affixed over the patient's xiphoid process to measure the positional variation of each individual BH. Using the BH within which the CT scan was performed as the reference, the authors quantified intra‐ and interfraction BH variations for each patient. To estimate the dosimetric impact of BH variations, the authors studied the positional correlation between the marker and the left breast using the FB CT and BH CT scans. The positional variations of 860 BHs as measured by the OTS were retrospectively incorporated into the original treatment plans to evaluate their dosimetric impact on breast and cardiac organs [heart and left anterior descending (LAD) artery].

Results:

The stability and localization accuracy of the OTS was within 0.2 mm along each direction. The mean intrafraction variation among treatment BHs was less than 2.8 mm in all directions. Up to 12.6 mm anteroposterior undershoot, where the patient's chest wall displacement of a BH is less than that of a reference BH, was observed with averages of 4.4, 3.6, and 0.1 mm in the anteroposterior, craniocaudal, and mediolateral directions, respectively. A high positional correlation between the marker and the breast was found in the anteroposterior and craniocaudal directions with respective Pearson correlation values of 0.95 and 0.93, but no mediolateral correlation was found. Dosimetric impact of BH variations on breast coverage was negligible. However, the mean heart dose, mean LAD dose, and max LAD dose were estimated to increase from 1.4/7.4/18.6 Gy (planned) to 2.1/15.7/31.0 Gy (delivered), respectively.

Conclusions:

In ABC‐assisted DIBH, large positional variation can occur in some patients, due to their different BH maneuvers. The authors’ study has shown that OTS can be a valuable tool for real‐time quality control of ABC‐assisted DIBH.
Amplitude and phase equalization of stimuli for click evoked auditory brainstem responses
Authors: Beutelmann Rainer , Laumen Geneviève , Tollin Daniel , Klump Georg M.
Published: December 2014

Although auditory brainstem responses (ABRs), the sound-evoked brain activity in response to transient sounds, are routinely measured in humans and animals there are often differences in ABR waveform morphology across studies. One possible reason may be the method of stimulus calibration. To explore this hypothesis, click-evoked ABRs were measured from seven ears in four Mongolian gerbils (Meriones unguiculatus) using three common spectrum calibration strategies: Minimum phase filter, linear phase filter, and no filter. The results show significantly higher ABR amplitude and signal-to-noise ratio, and better waveform resolution with the minimum phase filtered click than with the other strategies.
Quantitative appraisal of a new CCR model for entangled linear polymers
Authors: Ianniruberto Giovanni
Published: December 2014

Very recently, a new convective constraint release (CCR) single-mode (toy) model [Ianniruberto and Marrucci, J. Rheol. 58, 89–102 (2014)] has been proposed to account for the nowadays well-ascertained fact that flow induces some degree of disentanglement, the more so the faster is the flow [Baig et al., Macromolecules 43, 6886–6902 (2010)]. The previous work, successful in explaining some qualitative aspects of the nonlinear step strain response, is here extended to the multimode case by developing a model allowing for a spectrum of relaxation times in both orientational and stretch dynamics, the purpose being one of performing a quantitative comparison with literature data on nearly monodisperse linear polymers. Several data of relaxation after shear step strain and of time-dependent stress response in shear and elongational startup are considered. The overall agreement of the new multimode CCR model with data appears satisfactory.
A designed supramolecular protein assembly with in vivo enzymatic activity
Authors: Song Woon Ju , Tezcan F. Akif
Published: December 2014

The generation of new enzymatic activities has mainly relied on repurposing the interiors of preexisting protein folds because of the challenge in designing functional, three-dimensional protein structures from first principles. Here we report an artificial metallo-β-lactamase, constructed via the self-assembly of a structurally and functionally unrelated, monomeric redox protein into a tetrameric assembly that possesses catalytic zinc sites in its interfaces. The designed metallo-β-lactamase is functional in the
Escherichia coli
periplasm and enables the bacteria to survive treatment with ampicillin. In vivo screening of libraries has yielded a variant that displays a catalytic proficiency [(
k
cat
/
K
m
)/
k
uncat
] for ampicillin hydrolysis of 2.3 × 10
6
and features the emergence of a highly mobile loop near the active site, a key component of natural β-lactamases to enable substrate interactions.
One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light
Authors: Hwang Kuo Chu , Sagadevan Arunachalam
Published: December 2014

Nitric acid oxidation of cyclohexane accounts for ~95% of the worldwide adipic acid production and is also responsible for ~5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N
2
O). Here we report a N
2
O-free process for adipic acid synthesis. Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid.
Malicious exosomes
Authors: Anastasiadou Eleni , Slack Frank J.
Published: December 2014

Nanovesicles derived from cells of cancer patients carry microRNAs that initiate tumor growth in normal cells
Complete Genome Sequence for the Shellfish Pathogen Vibrio coralliilyticus RE98 Isolated from a Shellfish Hatchery
Authors: Richards Gary P. , Bono James L. , Watson Michael A. , Needleman David S.
Published: December 2014

Vibrio coralliilyticus
is a pathogen of corals and larval shellfish. Publications on strain RE98 list it as a
Vibrio tubiashii
; however, whole genome sequencing confirms RE98 as
V. coralliilyticus
containing a total of 6,037,824 bp consisting of two chromosomes (3,420,228 and 1,917,482 bp) and two megaplasmids (380,714 and 319,400 bp).
Draft Genome Sequence of Bradyrhizobium japonicum Is-34, Which Is Incompatible with
Rj4
Genotype Soybeans
Authors: Tsurumaru Hirohito , Kanesaki Yu , Hashimoto Syougo , Okizaki Kouhei , Yoshikawa Hirofumi , Yamakawa Takeo
Published: December 2014

We report here the draft genome sequence of
Bradyrhizobium japonicum
Is-34, which is incompatible with
Rj4
genotype soybeans. A candidate gene involved in this incompatibility was found to be present in this genome.
Complete Genome Sequence of Vibrio coralliilyticus Strain OCN014, Isolated from a Diseased Coral at Palmyra Atoll
Authors: Ushijima Blake , Videau Patrick , Poscablo Donna , Vine Veronica , Salcedo May , Aeby Greta , Callahan Sean M.
Published: December 2014

Vibrio coralliilyticus
is a marine gammaproteobacterium that has been implicated as an etiological agent of disease for multiple coral genera on reefs worldwide. We report the complete genome of
V. coralliilyticus
strain OCN014, isolated from a diseased
Acropora cytherea
colony off the western reef terrace of Palmyra Atoll.
Complete Genome Sequence of Cedecea neteri Strain SSMD04, a Bacterium Isolated from Pickled Mackerel Sashimi
Authors: Chan Kok-Gan , Tan Kian-Hin , Yin Wai-Fong , Tan Jia-Yi
Published: December 2014

We report here the complete genome sequence of
C. neteri
SSMD04, a strain isolated from pickled mackerel sashimi, sequenced by third-generation sequencing technology. To the best of our knowledge, this is the first documentation that reports the complete genome of
Cedecea neteri
.
Discontinuation of infliximab therapy in patients with Crohn's disease in sustained complete remission (the STOP IT study): protocol for a double-blind, randomised, placebo-controlled, multicentre trial
Authors: Buhl Sine Schnoor , Steenholdt Casper , Brynskov Jørn , Thomsen Ole Østergaard , Bendtzen Klaus , Ainsworth Mark Andrew
Published: December 2014

Introduction

Infliximab (IFX), a monoclonal chimeric antibody against tumour necrosis factor (TNF) α, is effective for induction and maintenance of remission in moderate to severe Crohn's disease. Discontinuation of IFX maintenance therapy in patients in remission should be considered in order to reduce the potential long-term side effects and lower costs.

Methods and analysis

This is a prospective, double-blind, randomised, placebo-controlled, multicentre study of patients with luminal Crohn’s disease who have been treated with IFX for at least 1 year and are in sustained complete clinical, biochemical and endoscopic remission (ie, Crohn's Disease Activity Index (CDAI) score <150, complete mucosal healing and biochemical markers of inflammation within the normal range). These patients are randomised to receive placebo infusions or continue IFX maintenance therapy. The primary end point is the proportion of patients in maintained remission after 48 weeks (def. CDAI <150).

Ethics and dissemination

It is estimated that the knowledge gained about how to optimally handle patients with Crohn’s disease in complete long-term sustained remission on IFX is proportionate to the risks and inconveniences related to participation in this study. Prolonged exposure to IFX may cause severe side effects and increased risk of malignancies. Conversely, IFX discontinuation should not unnecessarily create a high risk of relapse. Thus, empirical evidence is needed concerning the safety of discontinuing IFX once a patient exhibits sustained remission. Study results will be published in an English language scientific medical journal. The study is approved by the Danish Medicines Agency (EudraCT-number: 2012-002702-51) and the Regional Ethics Committee of Region Hovedstaden Denmark (Approval-number: H-4-2012-099). The project is reported to the Danish Data Protection Agency (ID-number: 2007-58-0015/HEH.750.89-27), registered at Clinicaltrials.gov, and monitored by independent GCP units for the University of Copenhagen, Odense and Aarhus. The current approved protocol is V.3.2, dated 1 June 2014.

Trial registration number

http://clinicaltrials.gov/show/NCT01817426.
Risk factors for acute exacerbations of COPD in a primary care population: a retrospective observational cohort study
Authors: Müllerová Hana , Shukla Amit , Hawkins Adam , Quint Jennifer
Published: December 2014

Objectives

To evaluate risk factors associated with exacerbation frequency in primary care. Information on exacerbations of chronic obstructive pulmonary disease (COPD) has mainly been generated by secondary care-based clinical cohorts.

Design

Retrospective observational cohort study.

Setting

Electronic medical records database (England and Wales).

Participants

58 589 patients with COPD aged ≥40 years with COPD diagnosis recorded between 1 April 2009 and 30 September 2012, and with at least 365 days of follow-up before and after the COPD diagnosis, were identified in the Clinical Practice Research Datalink. Mean age: 69 years; 47% female; mean forced expiratory volume in 1s 60% predicted.

Outcome measures

Data on moderate or severe exacerbation episodes defined by diagnosis and/or medication codes 12 months following cohort entry were retrieved, together with demographic and clinical characteristics. Associations between patient characteristics and odds of having none versus one, none versus frequent (≥2) and one versus frequent exacerbations over 12 months follow-up were evaluated using multivariate logistic regression models.

Results

During follow-up, 23% of patients had evidence of frequent moderate-to-severe COPD exacerbations (24% one; 53% none). Independent predictors of increased odds of having exacerbations during the follow-up, either frequent episodes or one episode, included prior exacerbations, increasing dyspnoea score, increasing grade of airflow limitation, females and prior or current history of several comorbidities (eg, asthma, depression, anxiety, heart failure and cancer).

Conclusions

Primary care-managed patients with COPD at the highest risk of exacerbations can be identified by exploring medical history for the presence of prior exacerbations, greater COPD disease severity and co-occurrence of other medical conditions.
Nutritional status and the gonadotrophic response to a polar expedition
Authors: Woods David R. , Delves Simon K. , Britland Sophie E. , Shaw Anneliese , Brown Piete E. , Bentley Conor , Hornby Simon , Burnett Anne , Lanham-New Sue A. , Fallowfield Joanne L.
Published: December 2014

Polar expeditions have been associated with changes in the hypothalamic–pituitary–testicular axis consistent with central hypogonadism (i.e., decreased testosterone, luteinising hormone (LH), and follicle stimulating hormone (FSH)). These changes are typically associated with body mass loss. Our aim was to evaluate whether maintenance of body mass during a polar expedition could mitigate against the development of central hypogonadism. Male participants (n = 22) from a 42-day expedition (British Services Antarctic Expedition 2012) volunteered to take part in the study. Body mass, body composition, and strength data were recorded pre- and postexpedition in addition to assessment of serum testosterone, LH, FSH, thyroid hormones, insulin-like growth factor 1 (IGF-1), and trace elements. Energy provision and energy expenditure were assessed at mid- and end-expedition. Daily energy provision was 6335 ± 149 kcal·day−1. Estimated energy expenditure midexpedition was 5783 ± 1690 kcal·day−1. Body mass and percentage body fat did not change between pre- and postexpedition. Total testosterone (nmol·L−1) (14.0 ± 4.9 vs. 17.3 ± 4.0, p = 0.006), calculated free testosterone (pmol·L−1) (288 ± 82 vs. 350 ± 70, p = 0.003), and sex hormone binding globulin (nmol·L−1) (33 ± 12 vs. 36 ± 11, p = 0.023) concentrations increased. LH and FSH remained unchanged. Thyroid stimulating hormone (TSH; IU·L−1) (2.1 ± 0.8 vs. 4.1 ± 2.1, p < 0.001) and free triiodothyronine (FT3; IU·L−1) (5.4 ± 0.4 vs. 6.1 ± 0.8, p < 0.001) increased while free thyroxine, IGF-1, and trace elements remained unchanged. Hand-grip strength was reduced postexpedition but static lift strength was maintained. Maintenance of body mass and nutritional status appeared to negate the central hypogonadism previously reported from polar expeditions. The elevated TSH and free FT3 were consistent with a previously reported “polar T3 syndrome”.
Positive interactions between moss cushions and vascular plant cover improve water economy on Öland’s alvar, Sweden
Authors: Sand-Jensen Kaj , Hammer Kathrine Jul , Madsen-Østerbye Mikkel , Dencker Tim , Kragh Theis
Published: December 2014

Dense moss cushions colonize bare limestone pavements on Öland’s alvar, southeastern Sweden. As these cushions grow larger and thicker and can store more water, they should physically protect and facilitate their own performance as well as the colonization by vascular plants. We tested these predictions by measuring the airflow and water economy of moss cushions. We found that cushions are imbedded in boundary layers formed by ground and moss surfaces. Near-surface flow was reduced immediately upwind and negligible downwind of the moss cushions, which should facilitate their centrifugal expansion. The calculated diffusion boundary layer was thin (<0.7 mm) above moss cushions exposed to free airflow of 1–6 m·s−1in accordance with substantial turbulence measured by small sensors at 0.5 cm distance from moss surfaces. Evaporation from the wetted cushions increased linearly with wind speed (0 and 8 m·s−1) in wind-tunnel experiments, and neither evaporation nor airflow followed standard formulas for objects in free flow. Higher wind speed reduced the diffusion boundary layer and simultaneously cooled the moss surface, thereby reducing the drop in water vapour concentration from moss surfaces to air. As desiccation of cushions progressed during three dry summer days, the profound decline of evaporation rate with cushion size gradually became positive when only large cushions still contained water. Water economy in relation to cushion size predicted that rehydrated large cushions retained photosynthesis for 80% and small cushions for only 50% of the time. A cover of the succulent plant Sedum album L. reduced sun and wind exposure and water loss from the moss surface. Sedum remained hydrated after mosses had dried out. Moss cushions and Sedum can, therefore, mutually benefit from each other’s water economy.
Structural and optical investigations of CdO-Na2CO3-H3BO3 glasses
Authors: Mohan Shaweta , Singh D.P. , Kaur Simranpreet
Published: December 2014

Glasses with composition xCdO-(40-x) Na2CO3-60H3BO3; x = 10, 20, 30 and 40 mol% were prepared by conventional melt-quenching technique and checked by XRD technique for their amorphous nature. An increase in density and refractive index of the samples with an increase in content of CdO has been observed and discussed. The optical absorption spectra of the glasses were recorded in the range 200–1100 nm and was used to find optical mobility gap, Urbach energy, and cut-off wavelength for each sample. The decrease in optical mobility gap with increase in CdO points towards the compactness of the structure with the addition of CdO. FTIR spectroscopy reveals the presence of trigonal and tetrahedral borate units, and the results indicate the conversion of BO3 to BO4 units with the increase in CdO content.
The effect of sex on humanin levels in healthy adults and patients with uncomplicated type 1 diabetes mellitus
Authors: Lytvyn Yuliya , Wan Junxiang , Lai Vesta , Cohen Pinchas , Cherney David Z.I.
Published: December 2014

Diabetes mellitus (DM) is associated with a loss of renal and vascular protection in women compared with men, but the responsible mechanisms are unclear. Recent experimental work implicated humanin (HN) as a novel cytoprotective hormone in DM. Our goal was to measure sex-related differences in HN levels in uncomplicated type 1 DM patients (T1D) and healthy controls (HC), as well as the interaction between HN, circulating neurohormones, and vascular function. Plasma HN, cGMP and aldosterone, blood pressure (BP), glomerular filtration rate, and effective renal plasma flow (inulin and para-aminohippurate) were measured in HC (11 men, 10 women) and T1D (23 men and 18 women) during clamped euglycemia (4–6 mmol·L–1). Plasma HN levels were generally lower in HC men by comparison with the women, but the differences were not statistically significant. In contrast, levels in the T1D men were higher compared with the T1D women (p = 0.026) and HC men (p < 0.0001). In the HC men, but not the women, HN correlated negatively with BP, but not with renal function, cGMP, or aldosterone. In the T1D men, HN negatively correlated with plasma cGMP. In the T1D women, HN did not correlate with neurohormones or vascular function. Future work should determine the role of HN in the pathogenesis of sex-related vascular function differences in DM.
Brown bears (Ursus arctos) as ecological engineers: the prospective role of trees damaged by bears in forest ecosystems
Authors: Zyśk-Gorczyńska E. , Jakubiec Z. , Wuczyński A.
Published: December 2014

Brown bears (Ursus arctos L., 1758) damage trees (mainly the cambium) during feeding and marking. It is thought that their stripping of bark and their subsequent foraging on sapwood can lead to substantial economic losses. However, the part played by this process in the ecosystem is still unknown. We hypothesize that brown bear foraging makes resources and habitats available to other species. We anticipated that wounds perpetrated by bears during foraging would attract saproxylic insects and consequently insectivorous birds. Bear wounds were searched for on trees in the Bieszczady Mountains (Polish Eastern Carpathians) from 2008 to 2011. We analyzed 278 wounds in silver firs (Abies alba Mill.) of different age classes: 43% of them had holes made by wood-boring insects and 33% had signs of woodpecker feeding. The presence of insect holes and woodpecker marks in the wound was found to depend on wound area, wound age, and tree circumference (insects only). In particular, the oldest wound age class (>5 years old) was associated with a high probability of occurrence of insects and woodpeckers. Insects were attracted by wounds of smaller area than woodpeckers. The density of insect holes (number of wood-boring insects) depended on the wound age and tree circumference. Insect densities in fresh wounds (<1 year old) were significantly lower than in the older age classes. The results show that bear-made wounds provide breeding and feeding sites for both insects and birds. Especially for woodpeckers (forest indicator species) and for saproxylic insects (mainly endangered species), brown bears may play an important role as niche constructors and ecological engineers. Therefore, it would be advisable to leave a considerable number of bear-wounded trees in the forest ecosystems for conservation purposes.
$\frac{{\rm SO}(2N)}{U(N)}$ Riccati–Hartree–Bogoliubov equation based on the SO(2N) Lie algebra of the fermion operators
Authors: Nishiyama Seiya , da Providência João
Published: December 2014

In this paper we present the induced representation of SO (2N) canonical transformation group and introduce [Formula: see text] coset variables. We give a derivation of the time-dependent Hartree–Bogoliubov (TDHB) equation on the Kähler coset space [Formula: see text] from the Euler–Lagrange equation of motion for the coset variables. The TDHB wave function represents the TD behavior of Bose condensate of fermion pairs. It is a good approximation for the ground state of the fermion system with a pairing interaction, producing the spontaneous Bose condensation. To describe the classical motion on the coset manifold, we start from the local equation of motion. This equation becomes a Riccati-type equation. After giving a simple two-level model and a solution for a coset variable, we can get successfully a general solution of time-dependent Riccati–Hartree–Bogoliubov equation for the coset variables. We obtain the Harish-Chandra decomposition for the SO (2N) matrix based on the nonlinear Möbius transformation together with the geodesic flow on the manifold.