bluuebunny/crossref_metadata_2025 huggingface dataset:
Periprosthetic Infection: Major Cause of Early Failure of Primary and Revision Total Knee Arthroplasty
Authors: Evangelopoulos Dimitrios S. , Ahmad Sufian S. , Krismer Anna M. , Albers Christoph E. , Hoppe Sven , Kleer Barbara , Kohl Sandro , Ateschrang Atesch
Published: October 2018

Revision total knee arthroplasty (RTKA) represents an effective treatment for failed TKA, but with less favorable outcomes. Considering the technical complexity and economic burden of RTKA procedures, it is mandatory to investigate current mechanisms and predictors for RTKA failure. The objective of this study is to evaluate the survivorship and determine the predominant causes of failure of RTKA. A total of 146 patients undergoing RTKA between 2003 and 2013 were identified from the institutional database. Revision was defined as surgery in which the whole prostheses (inlay and both femoral and tibial components) required exchange. Median follow-up was 6.3 ± 2.7 years (range: 2.2–10). Patient demographics, year of primary implantation, reasons for revision surgery, implant type, pain, knee mobility, systemic or local postoperative complications, and treatment of the complications were recorded and evaluated. Infection was a major cause of failure followed by aseptic loosening, instability, pain, malalignment, and inlay wear. Following RTKA, Knee Society Score (KSS) (knee score and functional score) demonstrated a significant improvement (p < 0.05). No significant difference in flexion, extension deficit, and KSS was detected between aseptic and septic primary TKAs preoperatively and following first RTKA. Reinfection rate of the septic primary TKAs was 5%. Infection was the major cause of a second revision, reaching as high as 50% in all cases. The results of this study support that septic failure of a primary TKA is likely to occur within the first 2 years following implantation. Septic failure of primary TKA does not influence survival of the revision prosthesis.
Moderate Interrater Reliability in the Diagnosis of Scaphoid Waist Fractures
Authors: Jørgensen Rasmus , Jensen Claus
Published: October 2018

Background Conventional radiographs have been shown to yield unreliable results in classifying scaphoid fractures. Computed tomography (CT) has been claimed to be the tool of choice in determining the treatment as well as fracture displacement.

Purpose The purpose of the study was to examine the interrater reliability and intrarater reproducibility in the decision-making of the treatment of scaphoid waist fractures.

Patients and Methods Fifty-one CT scans of scaphoid waist fractures were utilized. Seven orthopaedic surgeons with a particular interest in hand surgery independently scrutinized the scans classifying each in undisplaced, < 2 mm displaced, or > 2 mm displaced, and suggested a treatment of immobilization in cast or screw fixation. The Fleiss' and Cohen's kappa values using SPSS (Statistical Package for Social Science) version 24 were calculated and interpreted according to Landis and Koch.

Results The kappa value representing interrater reliability when choosing between operative or nonoperative treatment was 0.58. Interrater reliability of the distinction between < 2 mm displaced or > 2 mm displaced fractures was 0.61. On average 79.5% of the fractures were suggested treated nonoperatively and 20.5% operatively. Overall, intrarater reproducibility was 0.75 when classifying between < 2 mm displaced or > 2 mm displaced fractures. When choosing between operative or nonoperative treatment, intrarater reproducibility was 0.69.

Conclusion Moderate interrater reliability was found when choosing between nonoperative and operative treatment. The use of CT showed substantial reliability in the distinction between < 2 mm displaced and > 2 mm displaced fractures. Intrarater reproducibility was substantial when classifying between < 2 mm displaced and > 2 mm displaced fractures as well as when choosing between operative or nonoperative treatment.

Level of Evidence This is a Level III study.
The Influence of CYP3A4 Polymorphism in Sex Steroids as a Risk Factor for Breast Cancer
Authors: Veiga Melissa Gonzalez , Felizi Rogério Tadeu , Reis Dayane Guerino , Carelli Filho Ivo , Fernandes Cesar Eduardo , Souto Ricardo Peres do , Oliveira Emerson
Published: October 2018

Objective Epidemiological studies have shown evidence of the effect of sex hormones in the pathogenesis of breast cancer, and have suggested a relationship of the disease with variations in genes involved in estrogen synthesis and/or metabolism. The aim of the present study was to evaluate the association between the CYP3A4*1B gene polymorphism (rs2740574) and the risk of developing breast cancer.

Methods In the present case-control study, the frequency of the CYP3A4*1B gene polymorphism was determined in 148 women with breast cancer and in 245 women without the disease. The DNA of the participants was extracted from plasma samples, and the gene was amplified by polymerase chain reaction. The presence of the polymorphism was determined using restriction enzymes.

Results After adjusting for confounding variables, we have found that the polymorphism was not associated with the occurrence of breast cancer (odds ratio = 1.151; 95% confidence interval: 0.714–1.856; p = 0.564). We have also found no association with the presence of hormone receptors, with human epidermal growth factor receptor 2 (HER2) overexpression, or with the rate of tumor cell proliferation.

Conclusion We have not observed a relationship between the CYP3A4*1B gene polymorphism and the occurrence of breast cancer.
An Unusual Case of Choledochal Cyst
Authors: Pathak Manish , Saxena Rahul , Jayakumar T.K. , Sinha Arvind , Yadav Taruna
Published: October 2018

Choledochal cyst (CC) is an important surgical cause of jaundice in infants. Infantile variant of CC can mimic biliary atresia in clinical presentation. CC associated with biliary atresia is well described in literature. We encountered an atretic variant of CC that has not been described in literature ever. The characteristics of this unusual case, management, and proposed hypothesis to its pathogenesis are discussed here.
Sarcolemmal Alterations in Unloaded Rat Heart after Heterotopic Transplantation
Authors: Makino Naoki , Ganguly Paul , Elimban Vijayan , Dhalla Naranjan
Published: October 2018

Following heterotopic transplantation, the rat heart undergoes atrophy and exhibits delayed cardiac relaxation without any changes in contraction and systolic Ca2+ transients. Furthermore, the sarcoplasmic reticular Ca2+ uptake and release activities were reduced and Ca2+ influx through L-type Ca2+ channels was increased in the atrophied heart. Since Ca2+ movements at sarcolemma are intimately involved in the regulation of intracellular Ca2+ concentration, the present study was undertaken to test if sarcolemma plays any role to maintain cardiac function in the atrophied heart.The characteristics of sarcolemmal Ca2+ pump and Na+–Ca2+ exchange activities were examined in 8 weeks heterotopically isotransplanted rat hearts which did not support hemodynamic load and underwent atrophy. Sarcolemmal ATP (adenosine triphosphate)-dependent Ca2+ uptake and Ca2+-stimulated ATPase (adenosine triphosphatase) activities were increased without any changes in Na+–K+ ATPase activities in the transplanted hearts. Although no alterations in the Na+-dependent Ca2+ uptake were evident, Na+-induced Ca2+ release was increased in the transplanted heart sarcolemmal vesicles. The increase in Na+-induced Ca2+ release was observed at different times of incubation as well as at 5, 20, and 40 mM Na+. The sarcolemma from transplanted hearts also showed higher contents of phosphatidic acid, sphingomyelin, and cholesterol.These results indicate that increases in the sarcolemmal, Ca2+ transport activities in unloaded heart may provide an insight into adaptive mechanism to maintain normal contractile behavior of the atrophic heart.
Outcomes of Biliointestinal Bypass among Iranian Obese Patients
Authors: Naeini Seyed , Khalaj Alireza , Abbaszadeh-Kasbi Ali , Miri Seyed
Published: October 2018

Background There are several surgical approaches to treat obesity not cured with medical approaches. Each method has its advantages and complications. In here, we have conducted a study to evaluate complications of biliointestinal bypass surgery (BIBP).

Methods A prospective study was conducted in a private hospital from 2002 to 2016. Those patients, not previously operated for morbid obesity, were eligible. Mean follow-up period was 89 months ( ± 54 months; range: 73–108 months). Main outcome measures were weight, BMI (body mass index), concentrations of blood lipids and glucose, liver transaminases, and obesity-related comorbidities and complications.

Results Twenty-three consecutive patients with morbid obesity, including 16 women (69.7%) and seven men (31.3%) with mean age 38.47 ± 10 years (range: 26–57 years) underwent surgery. At the end of follow-up period, a mean BMI reduction of 12.2 kg/m2 kg/m2 (p < 0.001)] was observed. An excess weight loss (EWL) of 63% ( ± 34) was achieved at the end of the study. Additionally, total cholesterol and triglyceride levels decreased postoperative significantly. The main long-term complications were flatulence (60%), borborygmus (47.8%), mal odorous stool (30.4%), and diarrhea (21.7%). Revision rate was 4.34%. There were no cases with irreversible hepatic injury, deaths due to the surgery, or progressive renal failure.

Conclusion BIBP seems to be a safe, easily reversible, and one of valid therapeutic approaches in morbidly obese patients. BIBP has the potential to achieve durable weight loss and offers an improved quality of life.
Enterovesical Fistula Secondary to Transitional Cell Carcinoma of the Bladder
Authors: Bugeja Mark , Mizzi Christine , Ellul Ernest , Bugeja Simon , Mattocks Stephen
Published: October 2018

Although fistulae between the urinary bladder and the gastrointestinal tract are not uncommon, those caused by carcinoma of the urinary bladder are rare. This report describes the case of an 85 years old male who was diagnosed with a mass involving the small bowel and the urinary bladder during the course of investigation for recurrent urinary tract infections. At laparotomy, the presence of an enterovesical fistula involving the ileum and bladder was confirmed. Histopathological examination of the resected mass showed poorly differentiated urothelial carcinoma. No early postoperative complications were encountered and postoperative cystography showed healing of the bladder without evidence of leakage. Due to the patient's age and comorbidities, no further oncological treatment was offered. Three months later the patient was readmitted to hospital with a severe pneumonia to which he succumbed.
Retrosigmoid Craniotomy for the Removal of Left Sided Tentorial and Posterior Fossa Meningioma Combined with Microvascular Decompression for Hemifacial Spasm
Authors: Cheng Yu-Wen , Cheng Chun-Yu , Qazi Zeeshan , Sekhar Laligam N.
Published: October 2018

This 68-year-old woman presented with repeated episodes of bilateral hemifacial spasm with headache for 5 years and with recent progression of left sided symptoms. Preoperative imaging showed a left sided tentorial meningioma with brain stem and cerebellar compression. Left facial nerve was compressed by the vertebral artery (VA) and the right facial nerve by the anterior inferior cerebellar artery (AICA). This patient underwent left side retrosigmoid craniotomy and mastoidectomy. The cisterna magna was drained to relax the brain. The tumor was very firm, attached to the tentorium and had medial and lateral lobules. The superior cerebellar artery was adherent to the lateral lobule of the tumor and dissected away. The tumor was detached from its tentorial base; we first removed the lateral lobule. Following this, the medial lobule was also completely dissected and removed. The root exit zone of cranial nerve (CN) VII was dissected and exposed. The compression was caused both by a prominent VA and AICA. Initially, the several pieces of Teflon felt were placed for the decompression. Then vertebropexy was performed by using 8–0 nylon suture placed through the VA media to the clival dura. A further piece of Teflon felt was placed between cerebellopontine angle region and AICA. Her hemifacial spasm resolved postoperatively, and she discharged home 1 week later. Postoperative imaging showed complete tumor removal and decompression of left CN VII. This video shows the complex surgery of microsurgical resection of a large tentorial meningioma and microvascular decompression with a vertebropexy procedure.

The link to the video can be found at: https://youtu.be/N5aHN9CRJeM.
Impact of Graft Steatosis on Postoperative Complications after Liver Transplantation
Authors: Ahmed Emad , El-Badry Ashraf , Mocchegiani Federico , Montalti Roberto , Hassan Asem , Redwan Alaa , Vivarelli Marco
Published: October 2018

Background Steatotic grafts are more susceptible to ischemia-reperfusion injury than are normal grafts. Therefore, using steatotic grafts for liver transplantation (LT) is associated with high primary dysfunction and decreased survival rates. The aim of this study is to evaluate the impact of graft steatosis on post LT outcomes.

Methods A retrospective cohort analysis of 271 LT recipients from 2005 to 2016 was performed and patients were classified based on two types of steatosis, macrosteatosis (MaS), and microsteatosis (MiS). Each category was subdivided into three groups according to the degree of steatosis: no (< 5%), mild (≥5 to < 30%), and moderate (≥30 to ≤60%). The primary hospital stays and 6-month postoperative complications were analyzed by the Clavien–Dindo classification system. Additionally, patient and graft survivals were studied.

Results Significant differences were observed in grade III MaS (p-value = 0.019) and grade V MiS (p-value = 0.020). A high trend of early graft dysfunction was found in the moderate MaS and MiS groups; however, they were not statistically significant (p-value = 0.199 and 0.282, respectively). Interestingly, the acute cellular rejection (ACR) rate was found to be inversely proportional to the degree of steatosis in both categories but it did not reach a significant level (p-value = 0.161 and 0.111, respectively).

Conclusion Excellent post LT long-term outcomes using grafts with mild and moderate steatosis were determined. Further studies are needed to evaluate the newly proposed relationship between ACR and steatosis.
Lafora Disease: A Review of Molecular Mechanisms and Pathology
Authors: Verhalen Brandy , Arnold Susan , Minassian Berge
Published: October 2018

Lafora's disease is a neurodegenerative disorder caused by recessive loss-of-function mutations in the EPM2A (laforin glycogen phosphatase) or EPM2B (malin E3 ubiquitin ligase) genes. Neuropathology is characterized by malformed precipitated glycogen aggregates termed Lafora bodies. Asymptomatic until adolescence, patients undergo first insidious then rapid progressive myoclonus epilepsy toward a vegetative state and death within a decade. Laforin and malin interact to regulate glycogen phosphorylation and chain length pattern, the latter critical to glycogen's solubility. Significant gaps remain in precise mechanistic understanding. However, demonstration that partial reduction in brain glycogen synthesis near-completely prevents the disease in its genetic animal models opens a direct present path to therapy.
On the symmetry of a one-dimensional hydrogen atom
Authors: Ivetić Boris
Published: October 2018

We touch upon a long-standing question of the “true” one-dimensional hydrogen atom solution. From a symmetry point of view, the Kepler problem in the d ≥ 2 dimension is characterized by geometrical rotational symmetry, SO(d), as well as dynamical “accidental” SO(d + 1) symmetry. Because of the topology, these two symmetries are mutually exclusive in one dimension, regardless of the regularization employed, drawing one to a conclusion that the question of the “true” hydrogen atom in one dimension does not have an answer because a single dimension cannot support both of the symmetries of the Kepler problem. We argue our findings using a novel method to recover and classify solutions appearing in the literature according to the symmetry they respect. In particular, curious features of some of the solutions—double degeneracy and particle confinement—are directly attributed to the dynamical symmetry behind them.
Compensation of the pick-up fluxes on the plasma position control system when resonant magnetic perturbations are applied in J-TEXT
Authors: Huang Zhuo , Ding Yonghua , Wang Nengchao , Rao Bo , Li Da , Li Mao , Shen Chengshuo
Published: October 2018

In the J-TEXT tokamak the displacement coils, which serve as sensors for feedback control of plasma position, are significantly affected by the resonant magnetic perturbation (RMP) coils. To eliminate the deviation of plasma position caused by the RMP, the responses of the displacement coils to the RMP are studied with a view to compensate for the pick-up fluxes. Both the linear and eddy responses on the displacement coils are taken into account and adjusted accordingly. It was found that positional correction in the vertical direction was required when the RMP was operated in the poloidal mode m = 1 and horizontal positional correction was required when the RMP was operated in the m = 2 mode. When compensation was applied to the position control system, correction of plasma position was successfully achieved, as observed from soft X-ray imaging, as well as from the evolution of the current of the horizontal and vertical fields.
Astrocyte calcium signaling: Interplay between structural and dynamical patterns
Authors: Brazhe A. R. , Postnov D. E. , Sosnovtseva O.
Published: October 2018

Inspired by calcium activity in astrocytes, which is different in the cell body and thick branches on the one hand and thin branchlets and leaflets on the other hand, we formulate a concept of spatially partitioned oscillators. These are inhomogeneous media with regions having different excitability properties, with a global dynamics governed by spatial configuration of such regions. Due to a high surface-to-volume ratio, calcium dynamics in astrocytic leaflets is dominated by transmembrane currents, while somatic calcium dynamics relies on exchange with intracellular stores, mediated by IP3, which is in turn synthesized in the space nearby the plasma membrane. Reciprocal coupling via diffusion of calcium and IP3 between the two regions makes the spatial configuration an essential contributor to overall dynamics. Due to these features, the mechanisms governing the pattern formation of calcium dynamics differ from classical excitable systems with noise or from networks of clustered oscillators. We show how geometrical inhomogeneity can play an ordering role allowing for stable scenarios for calcium wave initiation and propagation.
The Warm Electron Beam Ion Trap (WEBIT): An instrument for ground calibration of space-borne x-ray spectrometers
Authors: Lockard T. E. , Magee E. W. , Layne D. A. , Leutenegger M. A. , Eckart M. E. , Hell N. , Brown G. V. , Beiersdorfer P.
Published: October 2018

The warm electron beam ion trap (WEBIT) at Lawrence Livermore National Laboratory is being developed as a pre-launch, ground calibration source for space-borne, high-throughput, high-resolution x-ray spectrometers, such as the x-ray imaging and spectroscopy mission Resolve quantum calorimeter. Historically, calibration sources for calorimeter spectrometers have relied on characteristic line emission from x-ray tubes, fluorescing metals, and radioactive sources. The WEBIT, by contrast, relies on emission from x-ray transitions in highly charged ions, for example, hydrogen-like and helium-like ions, whose energies are well known and whose line shapes are relatively simple. The WEBIT can create astrophysically relevant ions whose x-ray emission falls in the 0.3-12 keV science bandpass of Resolve and has a portable design advantageous for a calibration source. The WEBIT will be used to help calibrate Resolve’s instrumental line shape and gain scale as a function of various operational parameters during both detector subsystem level testing and instrumental level testing.
Active phase wave in the system of swarmalators with attractive phase coupling
Authors: Hong Hyunsuk
Published: October 2018

We consider a system of coupled swarmalators moving in two dimensional space and explore its collective behavior. Here the swarmalators represent the oscillators that can sync and swarm in space, following the previous study [O’Keeffe et al., Nat. Commun., 8, 1504 (2017)]. The internal state of each swarmalator is represented by its phase angle, and the swarmalators are free to move in the plane according to an equation of motion where the phase and spatial dynamics are coupled with each other. In particular, the phase coupling between the swarmalators is attractive (positive) one, so the coupling makes the swarmalators have their phase difference minimized. The collective behavior of the system is found to be different depending on the extent of the interplay between the phase and spatial dynamics: Specifically, when the extent of the interplay between the phase and spatial dynamics is so weak as to be negligible, the phase dynamics of our system recovers that of the conventional mean-field XY model. On the other hand, when a certain extent of the interplay is present, the system is found to exhibit the correlated phase where the overall order does not occur. Interestingly, it is found that the correlated phase is the same as the active phase wave found in the system of swarmalators with repulsive phase coupling [O’Keeffe et al., Nat. Commun., 8, 1504 (2017)]. We also find that the system exhibits two different phase transitions: One is the transition from the sync state to the active phase wave state, and the other one is the transition from the active phase wave state to the async state. We perform the finite-size scaling analysis and investigate the transition nature.
Fractional Fresnel coefficients for optical absorption in femtosecond laser-induced rough metal surfaces
Authors: Zubair Muhammad , Ang Yee Sin , Ooi Kelvin J. A. , Ang L. K.
Published: October 2018

The surface morphology of metal influences its optical absorptivity. Recent experiments have demonstrated that the femtosecond laser induced surface structures on metals could be dynamically controlled by the fluence of laser and the number of pulses. In this paper, we formulate an analytical model to calculate the optical absorption of a rough metallic surface by modeling the roughness as a fractal slab. For a given experimental image of the surface roughness, we characterize the roughness with a fractal parameter by using the box-counting method. With this parameter as an input, we calculate the absorption of an 800 nm laser pulse impinging on gold, copper, and platinum, and the calculated results show excellent agreements. In terms of physics, our model can be viewed as a fractional version of the Fresnel coefficients, and it will be useful for designing suitable surface structures to tune the light absorption on metals from purely reflective to highly absorptive based on different applications.
Chemical vapor sensing with CVD-grown monolayer MoSe2 using photoluminescence modulation
Authors: Campbell Paul M. , Friedman Adam L. , Hanbicki Aubrey T. , Sivaram Saujan V. , Kusterbeck Andrew J. , Nguyen Viet K. , Andrew McGill R.
Published: October 2018

Monolayer two-dimensional transition metal dichalcogenides (TMDs) such as MoSe2 are promising materials for chemical vapor sensing applications due to their unique monolayer structure, ease of fabrication, low cost, selectivity, sensitivity, and speed of response. To date, most chemical vapor and gas sensors that use TMDs are based on chemiresistive device properties. However, recent studies indicate that the optical properties, in particular the photoluminescence (PL), could be used to sense vapors as well. In this study, we examine the PL of MoSe2 while it is exposed to triethylamine, a strong electron donor and chemically relevant to nerve gas and explosive sensing. We observe a fast and significant decrease in the PL by as much as 75% during exposure. The PL begins to recover as soon as the vapor is switched off, indicating fast adsorption/desorption of the analyte. We analyze the data in terms of possible applications to chemical vapor sensing.
Attractor dynamics of a Boolean model of a brain circuit controlled by multiple parameters
Authors: Cabessa Jérémie , Villa Alessandro E. P.
Published: October 2018

Studies of Boolean recurrent neural networks are briefly introduced with an emphasis on the attractor dynamics determined by the sequence of distinct attractors observed in the limit cycles. We apply this framework to a simplified model of the basal ganglia-thalamocortical circuit where each brain area is represented by a “neuronal” node in a directed graph. Control parameters ranging from neuronal excitability that affects all cells to targeted local connections modified by a new adaptive plasticity rule, and the regulation of the interactive feedback affecting the external input stream of information, allow the network dynamics to switch between stable domains delimited by highly discontinuous boundaries and reach very high levels of complexity with specific configurations. The significance of this approach with regard to brain circuit studies is briefly discussed.
Optical images rotation and reflection with engineered orbital angular momentum spectrum
Authors: Li Fangshu , Xu Tianzhe , Zhang Wuhong , Qiu Xiaodong , Lu Xiancong , Chen Lixiang
Published: October 2018

According to the concept of digital spiral imaging, we reconstruct an arbitrary structured light beam with information based on orbital angular momentum (OAM) eigenstates, i.e., the Laguerre-Gaussian (LG) modes. We propose a method to realize the rotation and reflection of an image by imparting an extra phase factor to each constituent OAM mode. If each OAM mode is added by a time-varying phase, the structured light beams can be manipulated to rotate with a constant speed, similar to a reverse rotational Doppler effect. While making a conjugate transformation to each OAM mode and then adding a constant phase factor to them, the structured light beams can be flipped over along any axis. In experiment, we take two typical patterns, e.g., a smiley face and a letter “e,” to demonstrate the effectiveness of our scheme. The scheme presented in this work may find potential applications in optical micromanipulation and remote sensing.
Magnetic domain structure and domain wall analysis of ferromagnetic MnAs nanodisks selectively-grown on Si (111) substrates for spintronic applications
Authors: Horiguchi Ryoma , Hara Shinjiro , Iida Masaya
Published: October 2018

We report on the experimental and analytic results on magnetic domain and domain wall structures of MnAs nanodisks on AlGaAs nanopillar buffers selectively grown on Si (111) substrates partially covered with dielectric SiO2 thin film mask patterns using selective-area metal-organic vapor phase epitaxy. The results on the size dependence of the magnetic domain structure in MnAs nanodisks investigated by magnetic force microscopy show that a single domain is predominant in the MnAs nanodisks with an area of approximately 3 × 104 nm2 or less. It is also indicated that in the nanodisks with an area of approximately 6 × 104 nm2 or more, multiple domains, in particular, two magnetic domain structures with a 180° domain wall, are predominant. In addition, in the case of nanodisks with multiple domains, not only Néel walls but also Bloch walls are possibly formed, according to the detailed analyses of the magnetic force microscope images obtained. These results suggest that the magnetic domains and domain walls can be tuned by the control of the MnAs nanodisk size making them interesting nanostructures for spintronic applications.
Effects of collision and ion Mach number on magnetized plasma sheath with two species of positive ions
Authors: Basnet Suresh , Khanal Raju
Published: October 2018

We study the effect of collision and ion Mach number in a magnetized plasma sheath having two species of positive ions using fluid model. It is assumed that both the ions are singly ionized and in thermal equilibrium, and the electrons obey Boltzmann distribution. Our work signifies that the collision greatly affects the ion densities, which explicitly affect space charge density, net current density and the transverse drift of ions. On increasing the collisional frequency, ions accumulation point and current saturation point shift towards the sheath entrance (away from the wall). The ion Mach number affects potential profile and velocity profiles of both ion species. The magnitude of wall potential increases from 34 V to 45 V with the increase in ion Mach number from 0.3 to 0.9. Furthermore, it is shown that the effect of collisional force and Lorentz force is reduced at the sheath entrance by increasing the ion Mach number, which helps to control the flux of particles, momentum flow and energy flow towards the wall.
Transition of subcritical liquid jets in single and multicomponent systems
Authors: Ayyappan Dhanesh , Vaidyanathan Aravind , Muthukumaran C. K. , Nandakumar K.
Published: October 2018

The fundamental mechanisms which cause the behavior of a liquid jet to alter from classic spray atomization to diffusion-dominated mixing, especially in multicomponent systems at critical conditions, are investigated. In the present experimental study, the behavior of a subcritical laminar fluoroketone liquid jet injected into its own environment and in a mixture of N2-fluoroketone environment at varying Reynolds number (490-3700) and chamber pressure (subcritical to supercritical) conditions is investigated. The present work utilizes high-speed imaging techniques to understand the jet behavior, and the fractal analysis of the jet boundary is employed to comprehend the mixing nature of the liquid jet. The results show that the composition of fluids in the chamber environment plays a critical role in altering the jet behavior. The thermodynamic transition of the liquid jet depends upon the injecting Reynolds number and chamber pressure for a single component system, whereas in a binary component system, transition depends heavily on the partial pressure of the respective fluid in the chamber environment.
Low-dimensional paradigms for high-dimensional hetero-chaos
Authors: Saiki Yoshitaka , Sanjuán Miguel A. F. , Yorke James A.
Published: October 2018

The dynamics on a chaotic attractor can be quite heterogeneous, being much more unstable in some regions than others. Some regions of a chaotic attractor can be expanding in more dimensions than other regions. Imagine a situation where two such regions and each contains trajectories that stay in the region for all time—while typical trajectories wander throughout the attractor. Furthermore, if arbitrarily close to each point of the attractor there are points on periodic orbits that have different unstable dimensions, then we say such an attractor is “hetero-chaotic” (i.e., it has heterogeneous chaos). This is hard to picture but we believe that most physical systems possessing a high-dimensional attractor are of this type. We have created simplified models with that behavior to give insight into real high-dimensional phenomena.
A colored mean-field model for analyzing the effects of awareness on epidemic spreading in multiplex networks
Authors: Wu Qingchu , Xiao Gaoxi
Published: October 2018

We study the impact of susceptible nodes’ awareness on epidemic spreading in social systems, where the systems are modeled as multiplex networks coupled with an information layer and a contact layer. We develop a colored heterogeneous mean-field model taking into account the portion of the overlapping neighbors in the two layers. With theoretical analysis and numerical simulations, we derive the epidemic threshold which determines whether the epidemic can prevail in the population and find that the impacts of awareness on threshold value only depend on epidemic information being available in network nodes’ overlapping neighborhood. When there is no link overlap between the two network layers, the awareness cannot help one to raise the epidemic threshold. Such an observation is different from that in a single-layer network, where the existence of awareness almost always helps.
Numerical study of flow past an elliptic cylinder near a free surface
Authors: Subburaj Rahul , Khandelwal Prashant , Vengadesan S.
Published: October 2018

Flow past an elliptic cylinder near a free surface at a Reynolds number of 180 is studied numerically by varying parameters such as the angle of attack (AOA), aspect ratio (AR), submergence depth (hS), and Froude number (Fr). The immersed boundary method and level set method are used to study the flow. Simulations are performed for elliptic cylinders with angles of attack varying as −45°, 45°, and 90° and aspect ratios 2 and 4. A detailed investigation of quantities like the Strouhal number and forces provides an understanding on the complex flow interactions between the free surface and the elliptic cylinder of varying AOA and AR. Variation in the angle of attack brings substantial changes in the flow and vortex shedding pattern. The most significant of all changes observed with different AOAs is related to vortex shedding suppression at a depth of 0.096. Vortex shedding is suppressed at an AOA = 45°, but at −45°, metastable states appear, and at 90°, partial vortex shedding suppression occurs. Varying AR, on the other hand, does not bring any significant changes in the flow features, except for variation in mean forces and the Strouhal number.
Fabrication of gadolinium particle-based absorption gratings for neutron grating interferometry
Authors: Gustschin A. , Neuwirth T. , Backs A. , Schulz M. , Pfeiffer F.
Published: October 2018

The imaging performance of a neutron-based Talbot-Lau interferometer depends to a great extent on the absorption characteristics of the source and analyzer gratings. Due to its high neutron attenuation, gadolinium (Gd) is the preferred material for grating fabrication, but suffers from difficulties with deposition time, stability, uniformity, and selectivity into high aspect ratio structures. Here we present a simple alternative method of Gd deposition into grating structures based on metallic particle suspension casting and subsequent doctor-blading. Surface analysis by confocal and electron scanning microscopy shows that a nearly clear, particle free silicon interface of the grating structure over a large area could be reached. Additionally, characterization by neutron radiography confirms a high effective Gd height and homogeneity over the whole grating area. In particular, grating trenches well below 10 μm width could be successfully filled with Gd and deliver excellent absorbing performance down to the sub-2 Å wavelength range. The findings confirm that we obtained an effective binary absorption profile for the fabricated gratings which is of great benefit for grating-based neutron imaging.
Pulse shape analysis of individual gamma events—Correlation to energy resolution and the possibility of its improvement
Authors: Gridin S. , Onken D. R. , Williams R. T. , Swiderski L. , Mianowska Z. , Syntfeld-Kazuch A. , Moszynski M. , Gayshan V. , Vasiukov S. , Gektin A.
Published: October 2018

The measurement in 2014 of the nonproportionality of each decay component in CsI:Tl found opposite slopes of the fast and tail nonproportionality curves above about 10 keV. Somewhat earlier experiments on nonproportionality and resolution versus shaping time in NaI:Tl and CsI:Tl showed that proportionality and intrinsic resolution could be improved by including the slower “tail” component of the scintillation pulse. The observed opposing nonproportionality trends of fast and tail components constitute a basis for improvement of scintillator nonproportionality if they are added in a suitable linear combination. We examine whether combining the rise and decay components pulse by pulse with an algorithm of optimized proportions may also improve energy resolution. The premise is that a scintillation pulse carries more information about the particle stopping event than is conveyed in a simple measurement of the pulse height. In this work, we measured pulse shapes of individual gamma events in CsI:Tl and other scintillators using an eMorpho multichannel analyzer as a digital oscilloscope. Decomposition of every scintillation pulse into a rise and three exponential decay components allowed us to represent the pulse height spectrum as a linear combination of them. We found that energy resolution of CsI:Tl can be altered and improved through changing the weight of decay components in the linear combination.
Size dependent arsenic volatilization in ErAs nanoparticle powders
Authors: Lewis Matthew R. , Remy Roddel A. , Tew Bo E. , Zide Joshua M. O.
Published: October 2018

The thermal stability of ErAs nanoparticles and bulk-like powders, synthesized by pulsed laser ablation and direct reaction, respectively, is investigated up to 700 °C in N2. Thermogravimetric analysis and XRD are used to monitor the decomposition temperatures and crystalline compositions of the synthesized powders, respectively. Degradation of unagglomerated nanoparticle powders is observed at 350 °C accompanied by the crystallization of amorphous Er2O3. Mass balance analysis suggests that the mass loss occurs as a result of arsenic volatilization rather than congruent sublimation of ErAs. Conversely, micron-sized agglomerated particles grown by direct reaction show little evidence for degradation under similar thermal processing conditions. This significant decrease in ErAs stability compared to agglomerated powders suggests a size dependence on the degradation characteristics of ErAs.
Note: A 3D-printed flexure nanostage driven by piezo buzzers
Authors: Lee Sang Heon
Published: October 2018

A flexure nanostage capable of being manufactured at home at a low cost is proposed. A prototype of the said stage—fabricated using a three-dimensional (3D) printer—exhibited single degree-of-freedom motion. Limitations with regard to material, fabrication precision, and actuator force were overcome, and cross talk was reduced by designing flexure holes. Fabrication of such holes was exclusively facilitated by the use of 3D-printing technology. Experimental results demonstrate that the proposed stage can perform linear motion over a 10-μm distance over a voltage range of 30 V.
Radial energy flux during destabilized Alfvén eigenmodes
Authors: Kolesnichenko Ya. I. , Tykhyy A. V.
Published: October 2018

Equations which determine the density of the transverse energy flux generated by destabilized Alfvén eigenmodes in bounded plasmas are derived and analyzed. It is shown that the energy flux can be directed outwards or inwards. The value, direction, and radial distribution of the flux depend on the instability growth rate and location of the regions driving the instability. The transverse flux provides the growth of the mode amplitude in places where the instability drive is weak or absent. Moreover, it provides the spatial channeling of the energy [the energy transfer by the mode predicted by Kolesnichenko et al. [Phys. Rev. Lett. 104, 075001 (2010)]] from unstable regions to the regions where damping dominates. This improves the plasma energy confinement in the case of an inward flux and deteriorates the confinement in the contrary case. The energy fluxes during some Alfvén instabilities in the tokamak-reactor ITER and the Wendelstein 7-X stellarator are evaluated.
Molecular admixtures and impurities in atmospheric pressure plasma jets
Authors: Lietz Amanda M. , Kushner Mark J.
Published: October 2018

A more complete understanding of reactive chemistry generated by atmospheric pressure plasma jets (APPJs) is critical to many emerging medical, agricultural, and water treatment applications. Adding molecular gases to the noble working gas which flows through the jet is a common method to tailor the resulting production of reactive oxygen and nitrogen species (RONS). In this paper, results are discussed from a computational investigation of the consequences of H2O and O2 admixtures on the reactive chemistry of He APPJs flowing into humid air. This investigation, performed with a 2-dimensional plasma hydrodynamics model, addresses the RONS that are initially produced and the evolution of that chemistry on longer time scales. Without an admixture, the impurities in 99.999% pure helium are a major source of RONS. The addition of H2O decreases the production of reactive nitrogen species (RNS) and increases the production of reactive oxygen species (ROS). The addition of O2 significantly decreases the production of RNS, as well as hydrogen-containing ROS, but increases the production of ROS without hydrogen. This selectivity comes from the lower ionization energy of O2 compared to N2 and H2O, which then allows for charge exchange reactions. These charge exchange reactions change the RONS which are produced in the afterglow by dissociative recombination. The consequences of impurities were also examined. Humid air impurities as low as 10 ppm in the helium can account for 79%-98% of the production of most RONS in the absence of an intentional admixture. The degree to which the impurities affect the RONS production depends on the electrode configuration and can be reduced by molecular admixtures.
Logarithmically discretized model of bounce averaged gyrokinetics and its implications on tokamak turbulence
Authors: Xu Shaokang , Morel P. , Gürcan Ö. D.
Published: October 2018

A logarithmically discretized model, which consists of writing the system in log polar coordinates in wave-number domain and reducing the nonlinear interactions to a sum over neighboring scales that satisfy the triad conditions, is proposed for bounce averaged gyrokinetics, where the energy dependence is kept over a semi-regular grid that allows quadrature calculations in order to guarantee quasi-neutrality. The resulting model is a cheaper implementation of nonlinear multi-scale physics involving trapped electron modes, trapped ion modes, and zonal flows, which can handle anisotropy. The resulting wave-number spectrum is anisotropic at large scales, where the energy injection is clearly anisotropic, but is isotropised rapidly, leading generally towards an isotropic k−4 spectrum for spectral potential energy density for fully kinetic system and a k−5 spectrum for the system with one adiabatic species. Zonal flow damping, which is necessary for reaching a steady state in this model, plays an important role along with electron adiabaticity. Interesting dynamics akin to predator-prey evolution is observed among zonal flows and similarly large scale but radially elongated structures.
Effect of R-site substitution and the pressure on stability of RFe12: A first-principles study
Authors: Harashima Yosuke , Fukazawa Taro , Kino Hiori , Miyake Takashi
Published: October 2018

We theoretically study the structural stability of RFe12 with the ThMn12 structure (R: rare-earth element, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Lu, Y, or Sc, or group-IV element, Zr or Hf) based on density functional theory. The formation energy has a strong correlation with the atomic radius of R. The formation energy relative to simple substances decreases as the atomic radius decreases, except for R= Sc and Hf, while that relative to R2Fe17 and bcc Fe has a minimum for R= Dy. The present results are consistent with recent experimental reports in which the partial substitution of Zr at R sites stabilizes RFe12-type compounds with R= Nd or Sm. Our results also suggest that the partial substitution of Y, Dy, Ho, Er, or Tm for Nd or Sm is a possible way to enhance the stability of the ThMn12 structure. Under hydrostatic pressure, the formation enthalpy decreases up to ≈6 GPa and then starts to increase at higher pressures.
Quasiperiodic perturbations of heteroclinic attractor networks
Authors: Delshams Amadeu , Guillamon Antoni , Huguet Gemma
Published: October 2018

We consider heteroclinic attractor networks motivated by models of competition between neural populations during binocular rivalry. We show that gamma distributions of dominance times observed experimentally in binocular rivalry and other forms of bistable perception, commonly explained by means of noise in the models, can be achieved with quasiperiodic perturbations. For this purpose, we present a methodology based on the separatrix map to model the dynamics close to heteroclinic networks with quasiperiodic perturbations. Our methodology unifies two different approaches, one based on Melnikov integrals and the other one based on variational equations. We apply it to two models: first, to the Duffing equation, which comes from the perturbation of a Hamiltonian system and, second, to a heteroclinic attractor network for binocular rivalry, for which we develop a suitable method based on Melnikov integrals for non-Hamiltonian systems. In both models, the perturbed system shows chaotic behavior, while dominance times achieve good agreement with gamma distributions. Moreover, the separatrix map provides a new (discrete) model for bistable perception which, in addition, replaces the numerical integration of time-continuous models and, consequently, reduces the computational cost and avoids numerical instabilities.
Note: Improved spatial resolution of time-of-flight Thomson scattering of fusion devices
Authors: Nielsen P. , Gurdev L. L. , Dreischuh T. N. , Salzmann H. , Gowers C.
Published: October 2018

To measure the electron density and temperature of the outer half of the International Thermonuclear Experimental Reactor, it is currently planned to build two conventional Thomson scattering (TS) systems. It was recently shown that given the same new specifications and optimizing the optical design, a Light Detection and Ranging (LIDAR) TS system covering the full chord is feasible, too. In this note, we demonstrate that by deconvolving the data of the individual spectral channels, one can improve the spatial resolution of LIDAR TS to match that of the conventional core plasma system. We demonstrate that the scale length at the edge of an H-mode plasma is determined with reasonable accuracy.
High-order harmonic generation from 2D periodic potentials in circularly and bichromatic circularly polarized laser fields
Authors: Jia Guang-Rui , Wang Xin-Qiang , Du Tao-Yuan , Huang Xiao-Huan , Bian Xue-Bin
Published: October 2018

We studied the high-order harmonic generation (HHG) from 2D solid materials in circularly and bichromatic circularly polarized laser fields numerically by simulating the dynamics of single-active-electron processes in 2D periodic potentials. Contrary to the absence of HHG in the atomic case, circular HHGs below the bandgap with different helicities are produced from intraband transitions in solids with C4 symmetry driven by circularly polarized lasers. Harmonics above the bandgap are elliptically polarized due to the interband transitions. High-order elliptically polarized harmonics can be generated efficiently by both co-rotating and counter-rotating bicircular mid-infrared lasers. The cutoff energy, ellipticity, phase, and intensity of the harmonics can be tuned by the control of the relative phase difference between the 1ω and 2ω fields in bicircularly polarized lasers, which can be utilized as an ultrafast optical tool to image the structure of solids.