bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental shock metamorphism of terrestrial basalts: Agglutinate‐like particle formation, petrology, and magnetism
Authors: Badyukov Dmitrii D. , Bezaeva Natalia S. , Rochette Pierre , Gattacceca Jérôme , Feinberg Joshua M. , Kars Myriam , Egli Ramon , Raitala Jouko , Kuzina Dilyara M.
Published: November 2017

Hypervelocity impacts occur on bodies throughout our solar system, and play an important role in altering the mineralogy, texture, and magnetic properties in target rocks at nanometer to planetary scales. Here we present the results of hypervelocity impact experiments conducted using a two‐stage light‐gas gun with 5 mm spherical copper projectiles accelerated toward basalt targets with ~6 km s−1 impact velocities. Four different types of magnetite‐ and titanomagnetite‐bearing basalts were used as targets for seven independent experiments. These laboratory impacts resulted in the formation of agglutinate‐like particles similar in texture to lunar agglutinates, which are an important fraction of lunar soil. Materials recovered from the impacts were examined using a suite of complementary techniques, including optical and scanning electron microscopy, micro‐Raman spectroscopy, and high‐ and low‐temperature magnetometry, to investigate the texture, chemistry, and magnetic properties of newly formed agglutinate‐like particles and were compared to unshocked basaltic parent materials. The use of Cu‐projectiles, rather than Fe‐ and Ni‐projectiles, avoids magnetic contamination in the final shock products and enables a clearer view of the magnetic properties of impact‐generated agglutinates. Agglutinate‐like particles show shock features, such as melting and planar deformation features, and demonstrate shock‐induced magnetic hardening (two‐ to seven‐fold increases in the coercivity of remanence Bcr compared to the initial target materials) and decreases in low‐field magnetic susceptibility and saturation magnetization.
New evidence for the recent divergence of Devil's Hole pupfish and the plausibility of elevated mutation rates in endangered taxa
Authors: Martin Christopher H. , Höhna Sebastian
Published: November 2017

Sağlam et al. recently argued that the Devil's Hole pupfish (Cyprinodon diabolis), a conservation icon with the smallest known species range, was isolated 60 kya based on a new genomic data set. If true, this would be a radically long timescale for any species to persist at population sizes <500 individuals, in contrast to conservation genetics theory. However, here we argue that their analyses and interpretation are inappropriate. They placed highly restrictive prior distributions on divergence times, which do not appropriately model the large uncertainty and result in removing nearly all uncertainty from their analyses, and chose among models by assuming that pupfishes exhibit human mutation rates. We reanalysed their data with their same methods, only using an informative prior for the plausible range of mutation rates observed across vertebrates, including an estimate of the genomewide mutation rate from a pedigree analysis of cichlid fishes. In fact, Saglam et al.'s phylogenetic data support much younger median divergence times forC. diabolis, ranging from 6.2 to 19.9 kya, overlapping with our previous phylogenetic divergence time estimates of 2.5–6.5 kya. There are many reasons to suspect an even younger age and higher mutation rate inC. diabolis, as we previously estimated, due to their high metabolism, small adult size, small population size and severe environmental stressors. In conclusion, our results highlight the need for measuring mutation rate in this fascinating species and suggest that the ages of endangered taxa present in small, isolated populations may frequently be overestimated.
Theophylline as an adjunct to control malignant ventricular arrhythmia associated with early repolarization
Authors: Perrin Tilman , Guieu Regis , Koutbi Linda , Franceschi Frédéric , Hourdain Jérôme , Brignole Michele , Deharo Jean‐Claude
Published: November 2017

Early repolarization (ER) has been associated with an increased risk of sudden cardiac arrest. Interestingly, ventricular arrhythmias seem to be triggered by parasympathetic stimulation. In the present case report, we describe complete control of highly frequent malignant ventricular arrhythmias after adding theophylline to ineffective oral hydroquinidine and high‐rate pacing in a patient suffering from malignant ER. We hypothesize that the theophylline‐mediated enhanced beta‐adrenergic stimulation could reduce the transmural myocardial voltage discrepancy by increasing the inward ICa,L current.
The anatomy of the pediatric airway: Has our knowledge changed in 120 years? A review of historic and recent investigations of the anatomy of the pediatric larynx
Authors: Holzki Josef , Brown Karen A. , Carroll Robert G. , Coté Charles J.
Published: November 2017

Background

There is disagreement regarding the anatomy of the pediatric airway, particularly regarding the shape of the cricoid cartilage and the location of the narrowest portion of the larynx.

Aims

The aim of this review is to clarify the origin and the science behind these differing views.

Methods

We undertook a review of published literature, University Libraries, and authoritative textbooks with key search words and phrases.

Results

In vivo observations suggest that the narrowest portion of the airway is more proximal than the cricoid cartilage. However, in vitro studies of autopsy specimens measured with rods or calipers, confirm that the nondistensible and circular or near circular cricoid outlet is the narrowest level. These anatomic studies confirmed the classic “funnel” shape of the pediatric larynx. In vivo studies are potentially misleading as the aryepiglottic, vestibular, and true vocal folds are in constant motion with respiration. These studies also do not consider the effects of normal sleep, inhalation agents, and comorbidities such as adenoid or tonsil hypertrophy that cause some degree of pharyngeal collapse and alter the normal movement of the laryngeal tissues. Thus, the radiologic studies suggesting that the narrowest portion of the airway is not the cricoid cartilage may be the result of an artifact depending upon which phase of respiration was imaged.

Conclusion

In vivo studies do not take into account the motion of the highly pliable laryngeal upper airway structures (aryepiglottic, vestibular, and vocal folds). Maximal abduction of these structures with tracheal tubes or bronchoscopes always demonstrates a larger opening of the glottis compared to the outlet of the cricoid ring. Injury to the larynx depends upon ease of tracheal tube or endoscope passage past the cricoid cartilage and not passage through the readily distensible more proximal structures. The infant larynx is funnel shaped with the narrowest portion the circular or near circular cricoid cartilage confirmed by multiple in vitro autopsy specimens carried out over the past century.
Clinical implications of de Barsy syndrome
Authors: Warner Lindsay L. , Olsen David A. , Smith Hugh M.
Published: November 2017

Background

De Barsy syndrome is a rare, autosomal recessive syndrome characterized by cutis laxa, progeroid appearance, ophthalmic opacification, skeletal malformations, growth delays, and intellectual disability.

Aims

The aim of this case series is to identify the anesthetic considerations in the clinical management of patients with de Barsy syndrome.

Methods

A retrospective case review from 1968 to 2016 was performed at a single tertiary medical center to identify patients with de Barsy syndrome who underwent anesthesia for diagnostic and surgical procedures. We collected and analyzed the perioperative records and following data: age, sex, American Society of Anesthesiologists physical status, relevant comorbidities, surgical procedures, anesthesia management, and observed complications.

Results

Three patients underwent 64 unique anesthetics for a diverse collection of diagnostic and surgical procedures. An array of anesthetics and techniques were successfully used. Observations of the perioperative period found 7 episodes of intraoperative hyperthermia (>38.3°), a single difficult airway requiring fiberoptic bronchoscopic‐guided intubation, and repeatedly difficult intravenous access.

Conclusion

This expanded case series suggests that providers caring for patients with de Barsy syndrome should be aware of potential challenges with airway management, vascular access, and temperature monitoring.
Pressure‐flow characteristics of breathing systems and their components for pediatric and adult patients
Authors: Wenzel Christin , Schumann Stefan , Spaeth Johannes
Published: November 2017

Background

Breathing circuits connect the ventilator to the patients’ respiratory system. Breathing tubes, connectors, and sensors contribute to artificial airway resistance to a varying extent. We hypothesized that the flow‐dependent resistance is higher in pediatric breathing systems and their components compared to respective types for adults.

Aims

We aimed to characterize the resistance of representative breathing systems and their components used in pediatric patients (including devices for adults) by their nonlinear pressure‐flow relationship.

Methods

We used a physical model to measure the flow‐dependent pressure gradient (∆P) across breathing tubes, breathing tube extensions, 90°‐ and Y‐connectors, flow‐ and carbon dioxide sensors, water traps and reusable, disposable and coaxial breathing systems for pediatric and for adult patients. ∆P was analyzed for usual flow ranges and statistically compared at a representative flow rate of 300 mL∙s−1 (∆P300).

Results

∆P across pediatric devices always exceeded ∆P across the corresponding devices for adult patients (all P < .001 [no 95% CI includes 0]). ∆P300 across breathing system components for adults was always below 0.2 cmH2O but reached up to 4.6 cmH2O in a flow sensor for pediatric patients. ∆P300 was considerably higher across the reusable compared to the disposable pediatric breathing systems (1.9 vs 0.3 cmH2O, P < .001, [95% CI −1.59 to −1.56]).

Conclusion

The resistances of pediatric breathing systems and their components result in pressure gradients exceeding those for adults several fold. Considering the resistance of individual components is crucial for composing a breathing system matching the patient's needs. Compensation of the additional resistance should be considered if a large composed resistance is unavoidable.
Nitroglycerin: An unusual solution to intraoperative hypothermia in a 4‐year‐old burn patient
Authors: Goenaga Díaz Eduardo J. , Carter Jeffrey E. , Templeton T. Wesley
Published: November 2017

We describe the case of a 4‐year‐old child undergoing extensive burn surgery with refractory intraoperative hypothermia. A low‐dose nitroglycerin infusion was initiated to reverse vasoconstriction and improve heat absorption, after which the child's temperature steadily improved. In hypothermic burn patients, topical vasoconstrictors may hinder surface warming efforts. A vasodilator infusion may aid in warming the pediatric patient undergoing extensive excision and grafting.
Leaf cell membrane stability‐based mechanisms of zinc nutrition in mitigating salinity stress in rice
Authors: Tufail A. , Li H. , Naeem A. , Li T. X.
Published: November 2017

Excess salt affects about 955 million ha of arable land worldwide, and 49% of agricultural land is Zn‐deficient. Soil salinity and zinc deficiency can intensify plant abiotic stress. The mechanisms by which Zn can mitigate salinity effects on plant functions are not well understood.

We conducted an experiment to determine how Zn and salinity effects on rice plant retention of Zn, K+ and the salt ion Na+ affect chlorophyll formation, leaf cell membrane stability and grain yield. We examined the mechanisms of Zn nutrition in mitigating salinity stress by examining plant physiology and nutrition. We used native Zn‐deficient soils (control), four salinity (EC) and Zn treatments – Zn 10 mg·kg−1 (Zn10), EC 5 dS·m−1 (EC5), Zn10+EC5 and Zn15+EC5, a coarse rice (KS‐282) and a fine rice (Basmati‐515) in the study.

Our results showed that Zn alone (Zn10) significantly increased rice tolerance to salinity stress by promoting Zn/K+ retention, inhibiting plant Na+ uptake and enhancing leaf cell membrane stability and chlorophyll formation in both rice cultivars in native alkaline, Zn‐deficient soils (P < 0.05). Further, under the salinity treatment (EC5), Zn inputs (10–15 mg·kg−1) could also significantly promote rice plant Zn/K+ retention and reduce plant Na+ uptake, and thus increased leaf cell membrane stability and grain yield. Coarse rice was more salinity‐tolerant than fine rice, having significantly higher Zn/K+ nutrient retention.

The mechanistic basis of Zn nutrition in mitigating salinity impacts was through promoting plant Zn/K+ uptake and inhibiting plant Na+ uptake, which could result in increased plant physiological vigour, leaf cell membrane stability and rice productivity.
The Forest or the Trees? Tackling Simpson's Paradox with Classification Trees
Authors: Shmueli Galit , Yahav Inbal
Published: November 2017

Studying causal effects is central to research in operations management in manufacturing and services, from evaluating prevention procedures, to effects of policies and new operational technologies and practices. The growing availability of micro‐level data creates challenges for researchers and decision makers in terms of choosing the right level of data aggregation for inference and decisions. Simpson's paradox describes the case where the direction of a causal effect is reversed in the aggregated data compared to the disaggregated data. Detecting whether Simpson's paradox occurs in a dataset used for decision making is therefore critical. This study introduces the use of Classification and Regression Trees for automated detection of potential Simpson's paradoxes in data with few or many potential confounding variables, and even with large samples (big data). Our approach relies on the tree structure and the location of the cause vs. the confounders in the tree. We discuss theoretical and computational aspects of the approach and illustrate it using several real applications in e‐governance and healthcare.
Reservation Policies in Queues: Advance Deposits, Spot Prices, and Capacity Allocation
Authors: Oh Jaelynn , Su Xuanming
Published: November 2017

At firms such as restaurants, customers either make reservations in advance or join queues on the spot. Reservation holders may not show up, and walk‐ins have to wait. Using a game‐theoretic model between the firm and customers, this paper studies the following: (i) reservation deposits and service prices, and (ii) capacity allocation between reservations and walk‐ins. We have three main results: (i) When reservation no‐shows lead to wasted capacity that cannot be reallocated, the firm should front‐load all charges into the reservation deposit; (ii) The firm should charge a lower service price to reservation‐holders than to walk‐in customers when it decides to serve both; (iii) Less capacity should be allocated for reservations as the potential market size grows; with sufficiently large potential demand, the firm should stop taking reservations. Our results follow from key operational tradeoffs between reservations and queues: reservations permit 100% utilization, but queues operate at less than 100%; however, reservations have constant returns to scale, while queues enjoy increasing returns.
Information Technology and Sustainability: Evidence from an Emerging Economy
Authors: Khuntia Jiban , Saldanha Terence J. V. , Mithas Sunil , Sambamurthy V.
Published: November 2017

Research in operations management and information systems suggests that information technology (IT) can play an important role in managing operations that support environmentally sustainable (green) growth. Yet, few studies have empirically assessed the efficacy of green IT investments and initiatives, particularly in emerging economies such as India. This study examines the performance consequences of green IT investment and implementation in terms of energy conservation and profit impact. We analyze an archival dataset constructed from a survey of nearly 300 organizations in India, matched partially with objective data from a secondary source. We find that green IT investment is positively associated with a higher profit impact and that this association is partially mediated by a reduction in IT equipment energy consumption. In addition, we find that operations‐oriented green IT implementation is positively associated with both IT equipment energy consumption reduction and profit impact, whereas supplier‐oriented green IT implementation is positively associated only with reduction in IT equipment energy consumption. Our findings are robust to objective measures of firm‐level total income and profit after tax. We highlight opportunities for further research and discuss the implications of the study for managerial practice to encourage the implementation of green IT initiatives that promote greater environmental sustainability.
A Behavioral Remedy for the Censorship Bias
Authors: Tong Jordan , Feiler Daniel , Larrick Richard
Published: November 2017

Existing evidence suggests that managers exhibit a censorship bias: demand beliefs tend to be biased low when lost sales from stockouts are unobservable (censored demand) compared to when they are observable (uncensored demand). We develop a non‐constraining, easily implementable behavioral debias technique to help mitigate this tendency in demand forecasting and inventory decision‐making settings. The debiasing technique has individuals record estimates of demand outcomes (REDO): participants explicitly record a self‐generated estimate of every demand realization, allowing them to record a different value than the number of sales in periods with stockouts. In doing so, they construct a more representative sample of demand realizations (that differs from the sales sample). In three laboratory experiments with MBA and undergraduate students, this remedy significantly reduces downward bias in demand beliefs under censorship and leads to higher inventory order decisions.
Adaptation and validation of the VOICES (SF) questionnaire – for evaluation of end‐of‐life care in Sweden
Authors: O'Sullivan Anna , Öhlen Joakim , Alvariza Anette , Håkanson Cecilia
Published: November 2017

Objectives

Instruments for evaluating end‐of‐life care by voicing experiences of family members have previously been lacking in Sweden. The objective of this study was therefore to adapt and validate the VOICES (SF) questionnaire to evaluate quality of end‐of‐life care in Sweden. The VOICES (SF) [Views of Informal Carers – Evaluation of Services (Short form)] is a questionnaire about bereaved relatives' experiences of care in the last three months of life of a deceased family member.

Methods

This study was performed based on translation and back translation, cross‐cultural adaptation and content validation through cognitive interviewing and feedback from professional experts. For the cognitive interviews, a purposeful sample of 35 bereaved family members was recruited from home care, hospital wards and nursing homes. The participants were 13 men and 22 women (age ranged between 20 and 90+, mean age 66), who were relatives of persons who died from life‐limiting conditions. The bereaved family members' and the professional experts' concerns were summarised and analysed based on clarity, understanding, relevance, sensitivity and alternative response/wording.

Results

The main concerns emerging from the content validation related to the understanding and clarity of some of the questionnaire items', and a few concerns regarding the relevance of different response alternatives or items. Only two of the family members found it emotional to complete the questionnaire, and they still deemed completing it to be important and manageable.

Significance of results

The VOICES (SF) can be considered as feasible in the Swedish context, provided that cultural adaptation has been achieved, that is translation alone is not enough. The Swedish version will be available for healthcare professionals to use for quality monitoring of the care provided over the last three months in life, and for research, it enables national and cross‐national comparisons between different healthcare places and organisations.
On stochastic dependence
Authors: Meyer Joerg M.
Published: November 2017

The contrary of stochastic independence splits up into two cases: pairs of events being favourable or being unfavourable. Examples show that both notions have quite unexpected properties, some of them being opposite to intuition. For example, transitivity does not hold. Stochastic dependence is also useful to explain cases of Simpson's paradox.
Long‐term anesthetic protocol in rats: feasibility in electrophysiology studies in visual prosthesis
Authors: Barriga‐Rivera Alejandro , Tatarinoff Veronica , Lovell Nigel H. , Morley John W. , Suaning Gregg J.
Published: November 2017

Electrical stimulation of excitable cells provides therapeutic benefits for a variety of medical conditions, including restoration of partial vision to those blinded via some types of retinal degeneration. To improve visual percepts elicited by the current technology, researchers are conducting acute electrophysiology experiments, mainly in cats. However, the rat can provide a model of a range of retinal diseases and possesses a sufficiently large eye to be used in this field. This article presents a long‐term anesthetic protocol to enable electrophysiology experiments to further the development of visual prostheses. Six Long‐Evans rats (aged between 14 and 16 weeks) were included in this study. Surgical anesthesia was maintained for more than 15 h by combining constant intravenous infusion of ketamine (24.0–34.5 mg/kg/h), xylazine (0.9–1.2 mg/kg/h), and inhaled isoflurane in oxygen (<0.5%). Overall heart rate, respiratory rate, and body temperature remained between 187–233 beats/min, 45–58 breaths/min, and 36–38 °C, respectively. Neural responses to 200‐ms light pulses were recorded from the superior colliculus using a 32‐channel neural probe at the beginning and before termination of the experiment. Robust responses were recorded from distinct functional types of retinal pathways. In addition, a platinum electrode was implanted in the retrobulbar space. The retina was electrically stimulated, and the activation threshold was determined to be 5.24 ± 0.24 μC/cm2. This protocol may be used not only in the field of visual prosthesis research, but in other research areas requiring longer term acute experiments.
Differential processing in modality‐specific Mauthner cell dendrites
Authors: Medan Violeta , Mäki‐Marttunen Tuomo , Sztarker Julieta , Preuss Thomas
Published: November 2017

Key points

The present study examines dendritic integrative processes that occur in many central neurons but have been challenging to study in vivo in the vertebrate brain. The Mauthner cell of goldfish receives auditory and visual information via two separate dendrites, providing a privileged scenario for in vivo examination of dendritic integration.

The results show differential attenuation properties in the Mauthner cell dendrites arising at least partly from differences in cable properties and the nonlinear behaviour of the respective dendritic membranes.

In addition to distinct modality‐dependent membrane specialization in neighbouring dendrites of the Mauthner cell, we report cross‐modal dendritic interactions via backpropagating postsynaptic potentials.

Broadly, the results of the present study provide an exceptional example for the processing power of single neurons.

Animals process multimodal information for adaptive behavioural decisions. In fish, evasion of a diving bird that breaks the water surface depends on integrating visual and auditory stimuli with very different characteristics. How do neurons process such differential sensory inputs at the dendritic level? For that, we studied the Mauthner cells (M‐cells) in the goldfish startle circuit, which receive visual and auditory inputs via two separate dendrites, both accessible for in vivo recordings. We investigated whether electrophysiological membrane properties and dendrite morphology, studied in vivo, play a role in selective sensory processing in the M‐cell. The results obtained show that anatomical and electrophysiological differences between the dendrites combine to produce stronger attenuation of visually evoked postsynaptic potentials (PSPs) than to auditory evoked PSPs. Interestingly, our recordings showed also cross‐modal dendritic interaction because auditory evoked PSPs invade the ventral dendrite (VD), as well as the opposite where visual PSPs invade the lateral dendrite (LD). However, these interactions were asymmetrical, with auditory PSPs being more prominent in the VD than visual PSPs in the LD. Modelling experiments imply that this asymmetry is caused by active conductances expressed in the proximal segments of the VD. The results obtained in the present study suggest modality‐dependent membrane specialization in M‐cell dendrites suited for processing stimuli of different time domains and, more broadly, provide a compelling example of information processing in single neurons.
Linear Analysis of Converging Richtmyer–Meshkov Instability in the Presence of an Azimuthal Magnetic Field
Authors: Bakhsh Abeer , Samtaney Ravi
Published: November 2017

We investigate the linear stability of both positive and negative Atwood ratio interfaces accelerated either by a fast magnetosonic or hydrodynamic shock in cylindrical geometry. For the magnetohydrodynamic (MHD) case, we examine the role of an initial seed azimuthal magnetic field on the growth rate of the perturbation. In the absence of a magnetic field, the Richtmyer–Meshkov growth is followed by an exponentially increasing growth associated with the Rayleigh–Taylor instability (RTI). In the MHD case, the growth rate of the instability reduces in proportion to the strength of the applied magnetic field. The suppression mechanism is associated with the interference of two waves running parallel and antiparallel to the interface that transport vorticity and cause the growth rate to oscillate in time with nearly a zero mean value.
A Unified Design Approach to Repetitive Learning Control for Systems Subject to Fractional Uncertainties
Authors: Sun Mingxuan , Li He , Li Yanwei
Published: November 2017

Fractional uncertainties are involved in many practical systems. Currently, there is a lack of research results about such general class of nonlinear systems in the context of learning control. This paper presents a Lyapunov-synthesis approach to repetitive learning control (RLC) being unified due to the use of the direct parametrization and adaptive bounding techniques. To effectively handle fractional uncertainties, the estimation method for such uncertainties is elaborated to facilitate the controller design and convergence analysis. Its novelty lies in the less requirement for the knowledge about the system undertaken. Unsaturated- and saturated-learning algorithms are, respectively, characterized by which both the boundedness of the variables in the closed-loop system undertaken and the asymptotical convergence of the tracking error are established. Experimental results are provided to verify the effectiveness of the presented learning control.
A Theory Treatment of Pedestrian-Induced Lateral Vibration of Structure
Authors: Yang Qingshan , Gao Yanan
Published: November 2017

The lateral excessive sway motion caused by pedestrian traffic has attracted great public attention in the past decades years. However, the theories about exploring the effect of pedestrian on the lateral dynamic properties of structure are scarce. The new contribution of this paper is that a new pedestrian-structure system is proposed for exploring the effect of human on structural dynamic properties based on a sway assumption. Study shows that pedestrian deteriorates the natural frequency of structure and improves structural damping. The influence tendencies of pedestrian on structure can be supported by measurements. The further parametric study shows that the changes of human dynamic parameters have some evident impacts on structural dynamic performances. For example, the increase of leg damping can trigger an improvement of structural damping capacity. In addition, the walking step frequency closing structural harmonic natural frequency can incur the worst response. The increase of step width deteriorates lateral vibration and structural frequency but can slightly improve structural damping. One of essential reasons influencing structural lateral dynamic properties is the dynamic human system including body mass, damping, stiffness, and its motion behavior such as step frequency. This theory is proposed to analyze how pedestrian alters the lateral dynamic performances on those sensitive structures such as the footbridges or stadium bleachers. For example, how the variation of step width influences the change of natural frequency of structure?
Robust Voltage Control for an Electrostatic Micro-Actuator
Authors: Kandula Prasanth , Dong Lili
Published: November 2017

When a parallel-plate electrostatic actuator (ESA) is driven by a voltage source, pull-in instability limits the range of displacement to one-third of the gap between plates. In this paper, a nonlinear active disturbance rejection controller (NADRC) is originally developed on the ESA. Our control objectives are stabilizing and increasing the displacement of an ESA to 99.99% of its full gap. Most of the reported controllers in literature are based on linearized models of the ESAs and depend on detailed model information of them. However, the ESA is inherently nonlinear and has model uncertainties due to the imperfections of microfabrication and packaging. The NADRC consists of a nonlinear extended state observer (NESO) and a feedback controller. The NESO is used to estimate system states and unknown nonlinear dynamics for the ESA. Therefore, it does not require accurate model. We simulate the NADRC on a nonlinear ESA in the presences of external disturbance, system uncertainties, and noise. The simulation results verify the effectiveness of the controller by successfully extending the travel range of ESA beyond pull-in point. They also demonstrate that the controller is robust against both disturbance and parameter variations, and has low sensitivity to measurement noise. Furthermore, the stability for the control system with NADRC is theoretically proved.
Qualification of TA6V alloy cleaning processes using supercritical CO2 cleaning, from coupled SEM, XPS, and TPD analyses
Authors: Charton Sophie , Avril Ludovic , Besnard Rémy , Domenichini Bruno
Published: November 2017

Traditional industrial cleaning processes of titanium and titanium alloys use solvents which are potentially toxic and environmentally harmful. Carbon dioxide, which is nontoxic, nonflammable, recyclable, and available on a large scale, is a potential substitute for these solvents. Indeed, the zero surface tension of supercritical CO2 (SC-CO2) provides a significant advantage over liquid and aqueous solutions, and facilitates the access to small structures, while a high diffusion coefficient allows a fast rate of mass transfer. Moreover, its viscosity and density can be adjusted by tuning pressure and temperature. In this study, the performances of solvent-assisted SC-CO2 process are compared to traditional TA6V alloy cleaning processes. The efficiency of residual oil removal from a TA6V surface has been investigated by several techniques such as x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). While XPS gives a measure of the so-called relative atomic surface concentration of carbon, which is commonly used to characterize cleanliness of the surface in the nanometer range, both EPMA and SEM provide elementary analysis at μm3 range and are often associated with characterizing morphologies of protuberances. Temperature programmed desorption coupled to a quadrupole mass spectrometer has also been used to obtain qualitative information on the nature and the relative amounts of the species degassed from the polluted and cleaned material surfaces.
The desktop muon detector: A simple, physics-motivated machine- and electronics-shop project for university students
Authors: Axani S. N. , Conrad J. M. , Kirby C.
Published: November 2017

This paper describes the construction of a desktop muon detector, an undergraduate-level physics project that develops machine-shop and electronics-shop technical skills. The desktop muon detector is a self-contained apparatus that employs a plastic scintillator as the detection medium and a silicon photomultiplier for light collection. This detector can be battery powered and is used in conjunction with the provided software. The total cost per detector is approximately $100. We describe physics experiments we have performed, and then suggest several other interesting measurements that are possible, with one or more desktop muon detectors.
Computerized tomography platform using beta rays
Authors: Paetkau Owen , Parsons Zachary , Paetkau Mark
Published: November 2017

A computerized tomography (CT) system using a 0.1 μCi Sr-90 beta source, Geiger counter, and low density foam samples was developed. A simple algorithm was used to construct images from the data collected with the beta CT scanner. The beta CT system is analogous to X-ray CT as both types of radiation are sensitive to density variations. This system offers a platform for learning opportunities in an undergraduate laboratory, covering topics such as image reconstruction algorithms, radiation exposure, and the energy dependence of absorption.
How tall can gelatin towers be? An introduction to elasticity and buckling
Authors: Taberlet Nicolas , Ferrand Jérémy , Camus Élise , Lachaud Léa , Plihon Nicolas
Published: November 2017

The stability of elastic towers is studied through simple hands-on experiments. Using gelatin-based stackable bricks, one can investigate the maximum height a simple structure can reach before collapsing. We show through experiments and by using the classical linear elastic theory that the main limitation to the height of such towers is the buckling of the elastic structures under their own weight. Moreover, the design and architecture of the towers can be optimized to greatly improve their resistance to self-buckling. To this aim, the maximum height of hollow and tapered towers is investigated. The experimental and theoretical developments presented in this paper can help students grasp the fundamental concepts in elasticity and mechanical stability.
Newton's theory of the atmospheric refraction of light
Authors: Nauenberg Michael
Published: November 2017

Newton's unpublished theory for the trajectory of a light beam in a medium with varying index of refraction and spherical symmetry is reconstructed. He assumed that light consisted of particles (corpuscles), and derived Snell's refraction law from the assumption that the velocity of these corpuscles is proportional to the index of refraction of the medium, and the acceleration is proportional to its gradient. Surprisingly, Newton's theory leads to a relation for the refraction of light in such a medium that is identically the same as the modern theory based on the wave theory of light.
Optimizing the Launch of a Projectile to Hit a Target
Authors: Mungan Carl E.
Published: November 2017

Some teenagers are exploring the outer perimeter of a castle. They notice a spy hole in its wall, across the moat a horizontal distance x and vertically up the wall a distance y. They decide to throw pebbles at the hole. One girl wants to use physics to throw with the minimum speed necessary to hit the hole. What is the required launch speed v and launch angle θ above the horizontal?
A New Resonance Tube
Authors: Bates Alan
Published: November 2017

The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at the point where sound is perceived to have maximum loudness, or at the point where the amplitude of the standing wave has maximum value, namely an antinode. An antinode coincides with the position of the tuning fork, beyond the end of the air column, which consequently introduces an end correction. One way to minimize this end correction is to measure the distance between consecutive antinodes.
Pendulum Underwater – An Approach for Quantifying Viscosity
Authors: Leme José Costa , Oliveira Agostinho
Published: November 2017

The purpose of the experiment presented in this paper is to quantify the viscosity of a liquid. Viscous effects are important in the flow of fluids in pipes, in the bloodstream, in the lubrication of engine parts, and in many other situations. In the present paper, the authors explore the oscillations of a physical pendulum in the form of a long and lightweight wire that carries a ball at its lower end, which is totally immersed in water, so as to determine the water viscosity. The system used represents a viscous damped pendulum and we tried different theoretical models to describe it. The experimental part of the present paper is based on a very simple and low-cost image capturing apparatus that can easily be replicated in a physics classroom. Data on the pendulum’s amplitude as a function of time were acquired using digital video analysis with the open source software Tracker.
Analyzing Virtual Physics Simulations with Tracker
Authors: Claessens Tom
Published: November 2017

In the physics teaching community, Tracker is well known as a user-friendly open source video analysis software, authored by Douglas Brown. With this tool, the user can trace markers indicated on a video or on stroboscopic photos and perform kinematic analyses. Tracker also includes a data modeling tool that allows one to fit some theoretical equations of motion onto experimentally obtained data. In the field of particle mechanics, Tracker has been effectively used for learning and teaching about projectile motion, “toss up” and free-fall vertical motion, and to explain the principle of mechanical energy conservation. Also, Tracker has been successfully used in rigid body mechanics to interpret the results of experiments with rolling/slipping cylinders and moving rods. In this work, I propose an original method in which Tracker is used to analyze virtual computer simulations created with a physics-based motion solver, instead of analyzing video recording or stroboscopic photos. This could be an interesting approach to study kinematics and dynamics problems in physics education, in particular when there is no or limited access to physical labs. I demonstrate the working method with a typical (but quite challenging) problem in classical mechanics: a slipping/rolling cylinder on a rough surface.
Work and Inertial Frames
Authors: Kaufman Richard
Published: November 2017

A fairly recent paper resolves a large discrepancy in the internal energy utilized to fire a cannon as calculated by two inertial observers. Earth and its small reaction velocity must be considered in the system so that the change in kinetic energy is calculated correctly. This paper uses a car in a similar scenario, but considers the work done by forces acting over distances. An analysis of the system must include all energy interactions, including the work done on the car and especially the (negative) work done on Earth in a moving reference frame. This shows the importance of considering the force on Earth and the distance Earth travels. For calculation of work in inertial reference frames, the center of mass perspective is shown to be useful. We also consider the energy requirements to efficiently accelerate a mass among interacting masses.
Modeling as an Anchoring Scientific Practice for Explaining Friction Phenomena
Authors: Neilson Drew , Campbell Todd
Published: November 2017

Through examining the day-to-day work of scientists, researchers in science studies have revealed how models are a central sense-making practice of scientists as they construct and critique explanations about how the universe works. Additionally, they allow predictions to be made using the tenets of the model. Given this, alongside research suggesting that engaging students in developing and using models can have a positive effect on learning in science classrooms, the recent national standards documents in science education have identified developing and using models as an important practice students should engage in as they apply and refine their ideas with peers and teachers in explaining phenomena or solving problems in classrooms. This article details how students can be engaged in developing and using models to help them make sense of friction phenomena in a high school conceptual physics classroom in ways that align with visions for teaching and learning outlined in the Next Generation Science Standards. This particular unit has been refined over several years to build on what was initially an inquiry-based unit we have described previously. In this latest iteration of the friction unit, students developed and refined models through engaging in small group and whole class discussions and investigations.
Magnetic field ‘flyby’ measurement using a smartphone’s magnetometer and accelerometer simultaneously
Authors: Monteiro Martín , Stari Cecilia , Cabeza Cecilia , Marti Arturo C.
Published: November 2017

The spatial dependence of magnetic fields in simple configurations is a common topic in introductory electromagnetism lessons, both in high school and in university courses. In typical experiments, magnetic fields and distances are obtained taking point-by-point values using a Hall sensor and a ruler, respectively. Here, we show how to take advantage of the smartphone capabilities to get simultaneous measures with the built-in accelerometer and magnetometer and to obtain the spatial dependence of magnetic fields. We consider a simple setup consisting of a smartphone mounted on a track whose direction coincides with the axis of a coil. While the smartphone is moving on the track, both the magnetic field and the distance from the center of the coil (integrated numerically from the acceleration values) are simultaneously obtained. This methodology can easily be extended to more complicated setups.
Using guided inquiry to teach academic language
Authors: Parent Kelley
Published: November 2017

Introducing new physics phenomena through inquiry labs has been a staple of the successful physics teacher for years. Introducing new vocabulary through lab work, however, is less common. This paper offers an example of a simple and short lab that does just that, and one that I have found to be quite useful in my college prep physics courses to help students construct (and retain) functional definitions of the oft-transposed terms distance and displacement. A standard definition for displacement is a change in an object’s position, while distance would be the entire path traveled by the object, yet my students were using the two terms interchangeably, often saying distance when they really should have referred to displacement. I wanted them to be able to clearly distinguish between the two terms, so I designed a brief experiment that allows students the chance to engage with the concept. My colleagues and I have found that putting the students in charge of their learning with this simple activity helps the students better understand the difference between these two terms.
Molecular Characterization of an Endozoicomonas-Like Organism Causing Infection in the King Scallop (Pecten maximus L.)
Authors: Cano Irene , van Aerle Ronny , Ross Stuart , Verner-Jeffreys David W. , Paley Richard K. , Rimmer Georgina S. E. , Ryder David , Hooper Patrick , Stone David , Feist Stephen W.
Published: November 2017

One of the fastest growing fisheries in the UK is the king scallop (
Pecten maximus
L.), also currently rated as the second most valuable fishery. Mass mortality events in scallops have been reported worldwide, often with the causative agent(s) remaining uncharacterized. In May 2013 and 2014, two mass mortality events affecting king scallops were recorded in the Lyme Bay marine protected area (MPA) in Southwest England. Histopathological examination showed gill epithelial tissues infected with intracellular microcolonies (IMCs) of bacteria resembling
Rickettsia
-like organisms (RLOs), often with bacteria released in vascular spaces. Large colonies were associated with cellular and tissue disruption of the gills. Ultrastructural examination confirmed the intracellular location of these organisms in affected epithelial cells. The 16S rRNA gene sequences of the putative IMCs obtained from infected king scallop gill samples, collected from both mortality events, were identical and had a 99.4% identity to 16S rRNA gene sequences obtained from “
Candidatus
Endonucleobacter bathymodioli” and 95% with
Endozoicomonas
species.
In situ
hybridization assays using 16S rRNA gene probes confirmed the presence of the sequenced IMC gene in the gill tissues. Additional DNA sequences of the bacterium were obtained using high-throughput (Illumina) sequencing, and bioinformatic analysis identified over 1,000 genes with high similarity to protein sequences from
Endozoicomonas
spp. (ranging from 77 to 87% identity). Specific PCR assays were developed and applied to screen for the presence of IMC 16S rRNA gene sequences in king scallop gill tissues collected at the Lyme Bay MPA during 2015 and 2016. There was 100% prevalence of the IMCs in these gill tissues, and the 16S rRNA gene sequences identified were identical to the sequence found during the previous mortality event.

IMPORTANCE
Molluscan mass mortalities associated with IMCs have been reported worldwide for many years; however, apart from histological and ultrastructural characterization, characterization of the etiological agents is limited. In the present work, we provide detailed molecular characterization of an
Endozoicomonas
-like organism (ELO) associated with an important commercial scallop species.