bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptive estimation‐based TILC for the finite‐time consensus control of non‐linear discrete‐time MASs under directed graph
Authors: Lv Yunkai , Chi Ronghu , Feng Yuanjing
Published: October 2018

This work explores the consensus problems under the directed graph, variable learning gains, fast convergence and data‐driven control framework comprehensively and proposes an adaptive estimation‐based terminal iterative learning control for a nonlinear discrete‐time multi‐agent system (MAS) with a constant control input. A linear iteration‐incremental model is built by using an iterative dynamic linearisation where the unknown partial derivatives are estimated iteratively using I/O data. The learning control law is designed with both a constant learning gain and an iteration‐time‐varying learning gain. The constant one can be selected properly according to the estimation of partial derivatives and the varying one can be estimated from iteratively utilising I/O data. The result has also been extended to the nonlinear MAS with time‐varying control input and an extended adaptive estimation‐based TILC is developed by using time‐varying control input to enhance the control performance. A fast convergence of both the proposed methods is achieved by removing the unnecessary error constraints at other time instants than the endpoint. Both the proposed methods is apparently data‐driven since no model information is involved. The proposed finite time consensus control methods are confirmed to be effective under the directed graph through mathematic proof and extensive simulations.
Advancing usage‐based insurance – a contextual driving risk modelling and analysis approach
Authors: Hu Xianbiao , Zhu Xiaoyu , Ma Yu‐Luen , Chiu Yi‐Chang , Tang Qing
Published: October 2018

Most researchers and insurers evaluate driver's risks solely based on user global positioning system (GPS) trajectories. A new approach is proposed that collects individualised driving behaviour data from smartphone GPS module, combined with geographical network information and dynamic traffic conditions, to identify driving risk factors and evaluate driving behaviours in various contexts. The multi‐source data reveals real world activity patterns as to when, where and how an individual driver performs, from which performance measurements on both the trip and driver level are defined to measure the risks. In addition, the relationship between the defined driving performance measurements and accident rate can be examined and verified by combining the crash history of the drivers. Numeric analysis on the trip level demonstrates that driving behaviour is context‐sensitive, and the principal component analysis performed at the driver level shows that pedal operation and driving speed are the two most important performance measurements to characterise an individual's driving pattern. The subsequent correlation analysis of crash history and driving performances verify both pedal operation and driving speed are significantly related to more at‐fault accidents, which validates the modelling and analysis efforts. The findings of their study further existing knowledge and provide foundations for advanced pay‐as‐you‐drive‐and‐you‐save insurance pricing.
Discrimination of three or more partial discharge sources by multi‐step clustering of cumulative energy features
Authors: Zhu Ming‐Xiao , Wang Yan‐Bo , Chang Ding‐Ge , Zhang Guan‐Jun , Shao Xian‐Jun , Zhan Jiang‐Yang , Chen Ji‐Ming
Published: October 2018

Partial discharge (PD)‐based diagnosis is extensively employed in condition assessment of electrical equipment. In the case of multiple PD sources, discrimination of mixed signals is significant for reliable PD interpretation. To improve the separation performance of three or more PD sources, a multi‐step discrimination method is proposed. The cumulative energy functions are exploited to characterise wave shapes of PD signals, and width and sharpness features are extracted and classified to separate mixed patterns. With the objective of maximising a novel evaluation parameter of separation capability, the oblique line and length of structure element are optimised in the feature extraction stage. For the multi‐step discrimination method, the feature extraction and clustering procedures are repeatedly applied to the whole dataset, sub‐classes, sub‐sub‐classes etc., until no more clusters are generated. To evaluate the separation performance of the proposed algorithm, a mathematical model for PD pulse is proposed, which is the multiplication of Heidler enveloping function and an oscillating function whose frequency spectrum confirms Gaussian distribution. In the end, the multi‐step discrimination method is tested with PD current pulses and ultra‐high‐frequency signals of three artificial defects in transformer and gas‐insulated system, and the results prove the effectiveness of the proposed algorithm.
Polyacrylamide modification of halloysite nanotubes surface by inverse emulsion polymerisation and their application in reinforcing PTFE
Authors: Cheng Zhi‐Lin , Chang Xing‐Yu , Liu Zan , Qin Dun‐Zhong
Published: October 2018

This work exploited the abundant hydroxyl group of halloysite nanotubes (HNTs) to induce acrylamide‐polymerisation modification by inverse emulsion (water‐in‐oil), resulting in polyacrylamide (PAM)‐modified HNTs. The structure and dispersion properties of the modified HNTs were analysed by a series of characterisations. As a promising application of HNTs, polytetrafluoroethylene (PTFE) reinforced with HNTs‐PAM was prepared. The mechanical and tribological properties of the HNTs‐PAM/PTFE were intensively studied. The results show that the volume wear rate of the HNTs‐PAM/PTFE reduced 97.3% relative to PTFE. The wear resistance of HNTs in filling PTFE was desirable.
Dilution‐induced rapid synthesis of aqueous semiconductor quantum dots
Authors: Xiang Xinben , Shao Haibao , Dai Bo , Yu Jingwen , Deng Jiangxia , Ying Zhihua , Zheng Hui , Jiang Yuan
Published: October 2018

Traditionally, it is time‐consuming to synthesise large‐sized quantum dots (QDs) in the aqueous way. Herein, a fast and facile method for aqueous QD synthesis was developed. By simply diluting a high‐concentration precursor into low concentration with deionised water, QDs can nucleate and grow rapidly after heating. The influences of the dilution ratio, original precursor concentration and different ligands on the synthesis speed have been studied. Besides, the mechanism for the fast‐growth rate has also been elucidated.
Need for adaptive solutions to food vulnerability induced by fish scarcity and unaffordability in Senegal
Authors: Thiao Djiga , Leport Julie , Ndiaye Baba , Mbaye Adama
Published: October 2018

With a level of consumption among the highest in Africa (23.9 kg/person/year in 2013), Senegal is highly dependent on fish in terms of food security. There are many socio-economic factors that influence the importance of fish in the dietary habits of the population. However, because of the major changes that have gradually occurred in the fishing sector during the last two decades in terms of fishing overcapacity and overexploitation, the availability of fish has become an increasing challenge. In this article, we document the particular case of Senegal as a good example of how food vulnerability can result from the scarcity and increasing price of fish products. Using average monthly prices of four major fish products and a consumer price index time series from 1998 to 2014, in combination with information collected from the literature and the field, we demonstrate evidence of fish scarcity and analyze the temporal structure of fish product affordability. Before exploring the potential solutions, we outline the major drivers of shortage of fish in the country and the resulting responses of the most vulnerable groups of the population. Considering the global and national context, the main constraints and challenges for efficient adaptive strategies are also identified.
Früherkennung von Morbus Crohn anhand von oralen Manifestationen bei einer Patientin mit Marfan-Syndrom
Authors: Topbas Ayla , von Bremen Julia , Gattenlöhner Stefan , Ruf Sabine , Meyle Jörg
Published: October 2018

Ziel Dieser Fallbericht zeigt eine Patientin mit der Anamnese des Marfan-Syndroms (MFS) und einer atypischen gingivalen Hyperplasie, die zu einer frühen Diagnose von Morbus Crohn führte.

Material und Methoden Die Patientin zeigte typische kraniofaziale Manifestationen des Marfan-Syndroms. Zusätzlich stellte sich eine zunächst einseitige, dann symmetrische atypische Gingivahyperplasie im Frontzahnbereich dar. Die antiinfektiöse Parodontaltherapie verbesserte den überlagerten entzündlichen Teil des hyperplastischen Parodonts, aber die Hyperplasie blieb zu einem großen Teil bestehen.

Ergebnisse Die vermutete frühe Manifestation des Morbus Crohn im Oralbereich wurde histologisch durch eine Biopsie bestätigt. Morbus Crohn wurde anschließend durch eine internistische Endoskopie verifiziert.

Fazit Das Durchschnittsalter der Patienten, die sich einer kieferorthopädischen Behandlung unterziehen, entspricht dem Alter, in dem sich systemische Erkrankungen oft zum ersten Mal manifestieren. Orale Symptome können die ersten Anzeichen einer systemischen Erkrankung sein, wie in diesem Fall Morbus Crohn, und bieten somit die Möglichkeit zur Früherkennung durch Kieferorthopäden und Allgemeinzahnärzte.
Empfehlungen zur Diagnostik und Therapie bei krebskranken Kindern mit Fieber und Neutropenie – Vergleich zweier aktueller Leitlinien
Authors: Lehrnbecher Thomas , Groll Andreas , Agyeman Philipp , Ammann Roland , Attarbaschi Andishe , Behrends Uta , Berger Christoph , Hamprecht Axel , Hufnagel Markus , Laws Hans-Jürgen , Scheler Max , Temme Christian , Vieth Simon , Simon Arne
Published: October 2018

Krebskranke Kinder und Jugendliche haben aufgrund der Beeinträchtigung ihres Immunsystems ein erhöhtes Risiko für Infektionen. Die Neutropenie ist der wichtigste Risikofaktor für infektiöse Komplikationen, und Fieber in der Neutropenie stellt einen pädiatrischen Notfall dar. Während für Erwachsene mit Fieber in der Neutropenie bereits seit langem Leitlinien existieren, finden sich eigene Leitlinien für Kinder und Jugendliche erst seit wenigen Jahren. Sie sind von Bedeutung, da pädiatrische Patienten sich von Erwachsenen in vielen Punkten wie Grunderkrankung, Komorbidität sowie verfügbare Arzneimittel unterscheiden. Im vorliegenden Artikel werden die wichtigsten Gemeinsamkeiten und Unterschiede der jüngst erschienenen interdisziplinären Leitlinie der Deutschen Gesellschaft für Pädiatrische Infektiologie (DGPI) und Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH) sowie einer Leitlinie eines internationalen Expertenpanels für Kinder mit Fieber und Neutropenie herausgearbeitet und diskutiert.
Moderne Trainingstherapie bei Herz-Kreislauf-Erkrankungen
Authors: Edel Klaus
Published: October 2018

Körperliche Bewegung kann den Verlauf von Gefäßerkrankungen positiv beeinflussen und die Sterblichkeit bei Herz-Kreislauf-Erkrankungen senken. Entscheidend dabei ist neben der Häufigkeit vor allem die Intensität der Bewegung. Die Dosierung der Intensität des Sportprogramms orientiert sich entweder am Energieverbrauch oder an der aeroben Kraft, die während der körperlichen Aktivität angewendet wird. Welcher Sport ausgeübt wird, hat jedoch keinen eindeutigen Einfluss auf den Gesundheitseffekt.
Mit Pflanzenstoffen gegen erhöhtes Cholesterin
Authors: Schmiedel Volker
Published: October 2018

Pflanzliche Nahrungs- oder Heilmittel können auf 3 unterschiedliche Arten cholesterinsenkend wirken. Ballaststoffe in Pflanzen, wie zum Beispiel Apfelpektin oder Ballaststoffe in Flohsamen, sind in der Lage, Cholesterin oder dessen Derivate zu binden und damit die Resorption bzw. die Rückresorption zu behindern. Choleretisch wirkende Pflanzeninhaltsstoffe, zum Beispiel aus der Artischocke, verstärken die Ausscheidung von Cholesterin und Gallensäuren über die Galle. Bestimmte Pflanzeninhaltsstoffe wie Monacolin K aus dem Roten Reis behindern die körpereigene Cholesterinsynthese. Dieser Beitrag stellt die wichtigsten cholesterinsenkenden Heilpflanzen, deren Wirkprinzipien und die entsprechende Studienlage vor.
The Effect of Magnesium and Vitamin E Co-Supplementation on Glycemic Control and Markers of Cardio-Metabolic Risk in Women with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial
Authors: Jamilian Mehri , Sabzevar Niloufar Kazemi , Asemi Zatollah
Published: October 2018

Data on the effects of magnesium and vitamin E co-supplementation on glycemic control and markers of cardio-metabolic risk of patients with polycystic ovary syndrome (PCOS) were collected. This investigation was conducted to evaluate the effects of magnesium and vitamin E co-supplementation on glycemic control and markers of cardio-metabolic risk in women with PCOS. This randomized, double-blind, placebo-controlled trial was carried out on 60 women with PCOS, aged 18–40 years old. Participants were randomly divided into two groups to receive 250 mg/day magnesium plus 400 mg/day vitamin E supplements or placebo (n=30 each group) for 12 weeks. Fasting blood samples were taken at baseline and after the 12-week intervention to quantify related variables. After the 12-week intervention, compared with the placebo, magnesium and vitamin E co-supplementation led to a significant reduction in serum insulin levels (–1.1±3.0 vs. +1.6±3.7 μIU/ml, p=0.003) and homeostatic model of assessment for insulin resistance (–0.2±0.7 vs. +0.4±0.9, p=0.002), and a significant increase in the quantitative insulin sensitivity check index (+0.01±0.01 vs. –0.009±0.02, p=0.003). Furthermore, magnesium plus vitamin E supplementation significantly decreased serum triglycerides (–15.0±24.4 vs. +6.7±22.2 mg/dl, p=0.001) and VLDL-cholesterol concentrations (–3.0±4.9 vs. +0.6±2.4 mg/dl, P=0.01) compared with the placebo. A trend toward a greater decrease in total cholesterol levels was observed in magnesium plus vitamin E group compared to placebo group (–7.0±32.6 vs. +8.1±26.6 mg/dl, p=0.05). In conclusion, magnesium and vitamin E co-supplementation for 12 weeks to PCOS women had beneficial effects on parameters of insulin metabolism and few markers of cardio-metabolic risk.
Experiencia quirúrgica en el manejo de litiasis urinaria en la población pediátrica: estudio multicéntrico
Authors: Figueroa Victor , Torres Lynda , García Carlos , Prada Stefania , Castillo Mariangel , Pérez Jaime
Published: October 2018

Introducción y Objetivos La incidencia de litiasis urinaria en pediatría ha venido en aumento en los últimos años. Las indicaciones quirúrgicas están bien establecidas en la literatura, y con la disponibilidad actual de instrumental quirúrgico de calibre reducido diseñado para pacientes pediátricos, el manejo de esa entidad, ha tenido una evolución dramática. Mediante este estudio, se describe la experiencia quirúrgica de dos centros de referencia en el manejo de litiasis urinaria en población pediátrica.

Métodos se realizó un estudio multicéntrico, observacional descriptivo y retrospectivo. Se incluyeron pacientes menores de 18 años que fueron sometidos a algún manejo quirúrgico para enfermedad litiásica urinaria entre diciembre de 2010 y marzo de 2017. Los datos demográficos, evaluación pre-quirúrgica, características del cálculo, complicaciones y cálculos residuales fueron registrados, así́ como la tasa de éxito de los procedimientos. Se realizó un análisis estadístico descriptivo con medidas de frecuencia utilizando el software SPSS.

Resultados Un total de 18 pacientes y 19 procedimientos fueron incluidos. La media de edad fue 7,9 años (1–16), las presentaciones clínicas más comunes fueron dolor lumbar e infección de vías urinarias en un 42% y un 37% respectivamente. El diagnóstico se realizó mediante Urotac en la mayoría de pacientes (83%). La media del número y tamaño de los cálculos fue 1,9 (DE 3,1) y 14,8 mm (DE 10,92) respectivamente. La localización más común fue piélica (31%), seguido de uréter distal (26%), 2 (10%) pacientes tuvieron cistolitiasis y 4 (21%) pacientes tuvieron cálculos en diferentes localizaciones. Se realizaron 7 (37%) ureterolitotomías retrógradas endoscópicas (ULE) semirrígidas, 6 (31%) ULE flexibles, 3 (16%) cistolitotomías y 2 (10%) nefrolitotomías percutáneas. Un 53% de los casos, tenían catéter doble J previo al procedimiento y en un 68% de los casos, se dejó catéter doble J después del procedimiento. La tasa de éxito de las cirugías fue de un 89%. No se documentaron complicaciones intraoperatorias ni postoperatorias.

Conclusiones La litiasis urinaria en la población pediátrica es una entidad poco común. El tratamiento quirúrgico tiene alta tasa de éxito y es seguro. Se necesitan estudios con mayor nivel de evidencia para determinar el esquema terapéutico quirúrgico apropiado de esa población.
Impact of Exercise/Sport on Well-being in Congenital Bleeding Disorders
Authors: Fasoli Silvia , Gandini Giorgio , Giuffrida Anna , Franchini Massimo
Published: October 2018

Physical activity provides many benefits in patients with congenital bleeding disorders. Patients with hemophilia are encouraged to participate in exercise and sports, especially those patients receiving prophylaxis. Several publications and guidelines have explored this issue in hemophilia patients, evaluating in particular the impact of physical activity on patients' well-being and quality of life. The other rare congenital bleeding disorders are less studied; they are heterogeneous in terms of clinical bleeding phenotype, incidence of hemarthrosis, and arthropathy. Furthermore, prophylaxis in these patients is less common than in hemophilia patients, which must be considered when choosing the type of physical and sporting activity. In this review, the authors have analyzed the literature focusing their attention on those rare coagulation disorders that may be complicated by arthropathy and the role of exercise and sports in this context.
Influence of bulk and interfacial properties on shock compression of metal powders. II. Compaction of clusters of particles
Authors: de Brauer Alexia , Udaykumar H. S.
Published: October 2018

During compaction of large ensembles of metallic particles, the deformation and redistribution of the particles are strongly influenced by the bulk and interfacial properties of the interacting materials. Using a sharp-interface Eulerian approach, this paper studies the physics of shock compaction of clusters of particles by accurately capturing the interfacial dynamics of particle-particle interactions. The effect of disparity in bulk material properties such as impedance and yield strength and interfacial phenomena such as friction are quantified using interfacial area evolution as a measure of mixing of the materials. The results show that friction between the particles increases the mixing of the materials only for lower initial theoretical mean densities but does not significantly affect the overall dynamics of the compaction. The deformation and contact between the particles are most strongly influenced by the impedance mismatch of the materials. The difference in yield stress plays a minor role due to the predominance of pressure over deviatoric stresses. The results provide insights into the individual effects of impedance and yield stress mismatch between material pairs and also into the combined influence of mismatches in both properties. It is shown that apart from property mismatch, the average impedance of the mixture also plays a key role in mixing of the materials.
Relationship between permeability and diffusivity in polyethylene glycol hydrogels
Authors: Offeddu G. S. , Axpe E. , Harley B. A. C. , Oyen M. L.
Published: October 2018

The transport properties of hydrogels largely affect their performance in biomedical applications ranging from cell culture scaffolds to drug delivery systems. Solutes can move through the polymer mesh as a result of concentration gradients in the interstitial fluid or pressure gradients that move the fluid and solutes simultaneously. The relationship between the two modalities of transport in hydrogels can provide insight for the design of materials that can function effectively in the dynamic conditions experienced in vitro and in vivo, yet this correlation has not been previously elucidated. Here, fluorescence recovery after photobleaching (FRAP) is used to measure the diffusivity of dextran molecules of different size within polyethylene glycol hydrogels. Spherical indentation analyzed in a poroelastic framework is used to measure the permeability to fluid flow of the same hydrogels. It is found that while the diffusivity varies with exp(ξ-2), where ξ is the mesh size of the hydrogels, it also varies with exp(k-1), where k is the intrinsic permeability. For the same hydrogel structure, diffusive transport is affected by the solute size, while convective transport is unaffected. As spherical indentation is a reliable, quick and non-destructive testing method for hydrated soft materials, the relationship provides the means to faster assessment of the transport properties of hydrogels and, ultimately, of their effective use in biomedical applications.
Characterization and calibration of a multilayer coated Wolter optic for an imager on the Z-machine at Sandia National Laboratories
Authors: Wu M. , Kozioziemski B. , Vogel J. K. , Lake P. , Fein J. R. , Ampleford D. J. , Bourdon C. J. , Ayers J. , Bell P. , Bradley D. , Walton C. C. , Pickworth L. A. , Pivovaroff M. , Ames A. , Bruni R. , Romaine S. , Kilaru K. , Ramsey B.
Published: October 2018

The need for a time-resolved monochromatic x-ray imaging diagnostic at photon energies >15 keV has motivated the development of a Wolter optic to study x-ray sources on the Z-machine at Sandia National Laboratories. The work is performed in both the LLNL’s x-ray calibration facility and SNL’s micro-focus x-ray lab. Characterizations and calibrations include alignment, measurement of throughput within the field of view (FOV), the point-spread function within the FOV both in and out of focus, and bandpass in the FOV. These results are compared with ray tracing models, showing reasonable agreement.
A Wolter imager on the Z machine to diagnose warm x-ray sources
Authors: Fein J. R. , Ampleford D. J. , Vogel J. K. , Kozioziemski B. , Walton C. C. , Wu M. , Ball C. R. , Ames A. , Ayers J. , Bell P. , Bourdon C. J. , Bradley D. , Bruni R. , Dunham G. S. , Gard P. D. , Johnson D. , Kilaru K. , Kirtley C. , Lake P. W. , Maurer A. , Nielsen-Weber L. , Pickworth L. A. , Pivovaroff M. J. , Ramsey B. , Roberts O. J. , Rochau G. A. , Romaine S. , Sullivan M.
Published: October 2018

A new Wolter x-ray imager has been developed for the Z machine to study the emission of warm (>15 keV) x-ray sources. A Wolter optic has been adapted from observational astronomy and medical imaging, which uses curved x-ray mirrors to form a 2D image of a source with 5 × 5 × 5 mm3 field-of-view and measured 60-300-μm resolution on-axis. The mirrors consist of a multilayer that create a narrow bandpass around the Mo Kα lines at 17.5 keV. We provide an overview of the instrument design and measured imaging performance. In addition, we present the first data from the instrument of a Mo wire array z-pinch on the Z machine, demonstrating improvements in spatial resolution and a 350-4100× increase in the signal over previous pinhole imaging techniques.
Design and raytrace simulations of a multilayer-coated Wolter x-ray optic for the Z machine at Sandia National Laboratories
Authors: Vogel J. K. , Pivovaroff M. J. , Kozioziemski B. , Walton C. C. , Ayers J. , Bell P. , Bradley D. , Descalle M.-A. , Hau-Riege S. , Pickworth L. A. , Ampleford D. J. , Ball C. R. , Bourdon C. J. , Fein J. R. , Gard P. D. , Maurer A. , Wu M. , Ames A. , Bruni R. , Romaine S. , Kilaru K. , Roberts O. J. , Ramsey B.
Published: October 2018

Recent breakthroughs in the fabrication of small-radii Wolter optics for astrophysics allow high energy density facilities to consider such optics as novel x-ray diagnostics at photon energies of 15-50 keV. Recently, the Lawrence Livermore National Laboratory, Sandia National Laboratories (SNL), the Smithsonian Astrophysical Observatory, and the NASA Marshall Space Flight Center jointly developed and fabricated the first custom Wolter microscope for implementation in SNL’s Z machine with optimized sensitivity at 17.5 keV. To achieve spatial resolution of order 100-200 microns over a field of view of 5 × 5 × 5 mm3 with high throughput and narrow energy bandpass, the geometry of the optic and its multilayer required careful design and optimization. While the geometry mainly influences resolution and the field of view of the diagnostic, the mirror coating determines the spectral response and throughput. Here we outline the details of the design and fabrication process for the first multilayer-coated Wolter I optic for SNL’s Z machine (Z Wolter), including its W/Si multilayer, and present results of raytrace simulations completed to predict and verify the performance of the optic.
The upgraded JET gamma-ray cameras based on high resolution/high count rate compact spectrometers
Authors: Rigamonti D. , Broslawski A. , Fernandes A. , Figueiredo J. , Giacomelli L. , Gorini G. , Gosk M. , Kaveney G. , Kiptily V. , Korolczuk S. , Murari A. , Nocente M. , Pereira R. C. , Popovichev S. , Santos B. , Urban A. , Zychor I. , Tardocchi M. ,   JET Contributors
Published: October 2018

The JET gamma-ray cameras have been recently upgraded within the gamma-ray camera upgrade project in support of development of JET high performance deuterium plasma scenarios and in preparation of deuterium-tritium experiments. New, dedicated detectors based on a LaBr3 crystal and silicon photo-multipliers have been developed and replaced pre-existing CsI detectors in all 19 channels. The new instrument gives opportunity of making two-dimensional gamma-ray measurements with a counting rate capability exceeding 1 MCounts/s (MCps) and energy resolution better than 5% at 1.1 MeV. The upgrade is of relevance for fast ion and runaway electron physics studies in high performance deuterium discharges and also in plasmas with tritium at neutron yields in the range up to about 5 × 1017 n/s.
Generation of THz radiation by parametric coupling of laser and Trivelpiece–Gould mode
Authors: Dewan Himani , Singh M. , Uma R. , Sharma R. P.
Published: October 2018

A scheme to generate terahertz radiation is proposed, wherein the high power, perpendicular-extraordinary laser pump (X-mode) (ω0) parametrically decays into the Trivelpiece-Gould (TG) (ω1) mode and kinetic Alfvén wave (ω2) at an oblique angle with the external magnetic field. The nonlinear interaction amongst the three interacting waves leads to the existence of quasi-static ponderomotive force. Furthermore, under the influence of this force, electrons acquire nonlinear oscillatory velocity. A strong transient current is generated by the nonlinear coupling of laser velocity and TG density perturbation. This nonlinear current drives a wave, whose frequency is obtained in the terahertz range (ω2=ω0−ω1) after optimizing various laser-plasma parameters. For the resonant excitation of the wave, the requisite phase matching condition is shown by modelling the parallelogram, which follows the principle of conservation of energy and momentum simultaneously. The coupling coefficients for the three-wave interaction process along with the growth rate of decay instability are investigated.
Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)
Authors: Donovan D. C. , Unterberg E. A. , Stangeby P. C. , Zamperini S. , Auxier J. D. , Rudakov D. L. , Wampler W. R. , Zach M. , Abrams T. , Duran J. D. , Elder J. D. , Neff A. L.
Published: October 2018

Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces and oriented normal to the magnetic field, were inserted at the outboard mid-plane of DIII-D to study divertor tungsten (W) transport in the Scrape-Off Layer (SOL). Each CP collects particles along field lines with different parallel sampling lengths (determined by the rod diameters and SOL transport) giving radial profiles from the main wall inward to R-Rsep ∼ 6 cm. The CPs were deployed in a first-of-a-kind experiment using two toroidal rings of distinguishable isotopically enriched, W-coated divertor tiles installed at 2 poloidal locations in the divertor. Post-mortem Rutherford backscatter spectrometry of the surface of the CPs provided areal density profiles of elemental W coverage. Higher W content was measured on the probe side facing along the field lines toward the inner target indicating higher concentration of W in the plasma upstream of the CP, even though the W-coated rings were in the outer target region of the divertor. Inductively coupled plasma mass spectroscopy validates the isotopic tracer technique through analysis of CPs exposed during L-mode discharges with the outer strike point on the isotopically enriched W coated-tile ring. The contribution from each divertor ring of W to the deposition profiles found on the mid-plane collector probes was able to be de-convoluted using a stable isotope mixing model. The results provided quantitative information on the W source and transport from specific poloidal locations within the lower divertor region.
Whistler envelope solitons. I. Dynamics in inhomogeneous plasmas
Authors: Krafft C. , Volokitin A. S.
Published: October 2018

A self-consistent Hamiltonian model based on equations describing the coupled dynamics of whistler and lower frequency waves in inhomogeneous plasmas is built. On this basis, different aspects of whistler turbulence are studied, concerning mainly the development of modulational instabilities and the dynamics of envelope solitons in irregular plasmas. Numerical simulations based on the model show that modulational instabilities can lead to the generation of a beating of stable nonlinear whistlers propagating with a speed near the group velocity. The whistler envelope soliton is determined analytically, and its propagation in plasmas presenting random density fluctuations and weakly irregular density structures of different scales and amplitudes is studied, showing that the envelope is very weakly affected by these inhomogeneities, whereas the wavelengths and the amplitudes of the phase oscillations strongly vary. Moreover, simulations show for the first time that two whistler solitons moving with different but close velocities and colliding one with the other remain unchanged after this collision, independently of their initial amplitudes and velocities. Finally, we study the dynamics of sonic whistler envelope solitons and show that the propagation of their lower frequency perturbation is governed by a KdV-type equation.
On semiclassical Fourier integral operators, Schrödinger propagators and coherent states
Authors: Elong Ouissam , Robert Didier , Senoussaoui Abderrahmane
Published: October 2018

In this paper, we introduce a class of semiclassical Fourier integral operators using the Fourier-Bargmann transform. We will show that the propagator defined by the solution of the time dependent Schrödinger equation with subquadratic Hamiltonian H(t) is a semiclassical Fourier integral operator of order 0 associated to the Hamilton flow generated by the classical Hamiltonian H(t).
The magnetoelectric MEE-effect in the SmFe3(BO3)4 multiferroic in dc and ac electric fields
Authors: Freydman A. L. , Erofeev D. A. , Temerov V. L. , Gudim I. A.
Published: October 2018

The inverse magnetoelectric MEE-effect in the SmFe3(BO3)4 single-crystal sample in an applied electric field has been studied. The electric field E consists of two components: a constant one, e0, and a variable one, e × cos(ωt). The investigated compound evokes great interest due to the existence of both linear and quadratic contributions to the magnetoelectric effect. According to theoretical analysis, the effective susceptibility of the first harmonic of magnetic moment oscillations depends on the dc electric field component e0. Indeed, according to the measurement data, the dc field e0 significantly affects the MEE-effect first-harmonic amplitude: depending on the e0 sign, these oscillations can be either amplified or suppressed. This offers an opportunity for controlling the magnetic moment oscillation amplitude at the applied electric field frequency, including the signal modulation, which is promising for application. In the applied dc field e0, a slight change in the susceptibility of the MEE-effect term quadratic to the electric field was detected. The mathematical apparatus used correctly describes the qualitative dependence of the MEE-effect amplitude on the dc field e0, while the quantity appears to be approximately twofold overestimated.
Conformational change of a biomolecule studied by the weighted ensemble method: Use of the diffusion map method to extract reaction coordinates
Authors: Fujisaki Hiroshi , Moritsugu Kei , Mitsutake Ayori , Suetani Hiromichi
Published: October 2018

We simulate the nonequilibrium ensemble dynamics of a biomolecule using the weighted ensemble method, which was introduced in molecular dynamics simulations by Huber and Kim and further developed by Zuckerman and co-workers. As the order parameters to characterize its conformational change, we here use the coordinates derived from the diffusion map (DM) method, one of the manifold learning techniques. As a concrete example, we study the kinetic properties of a small peptide, chignolin in explicit water, and calculate the conformational change between the folded and misfolded states in a nonequilibrium way. We find that the transition time scales thus obtained are comparable to those using previously employed hydrogen-bond distances as the order parameters. Since the DM method only uses the 3D Cartesian coordinates of a peptide, this shows that the DM method can extract the important distance information of the peptide without relying on chemical intuition. The time scales are compared well with the previous results using different techniques, non-Markovian analysis and core-set milestoning for a single long trajectory. We also find that the most significant DM coordinate turns out to extract a dihedral angle of glycine, and the previously studied relaxation modes are well correlated with the most significant DM coordinates.
Stable and unstable miscible displacement of a shear-thinning fluid at low Reynolds number
Authors: Soori Tejaswi , Ward Thomas
Published: October 2018

We present the results of experiments performed for the displacement of an aqueous low-concentration polymer solution that initially fills a capillary tube (diameter < 1 mm), using water. Aqueous carboxymethyl-cellulose polymer solutions were prepared at initial concentration 0.5 < c0 < 0.75 (w/w). Polymer concentrations are low such that the displaced fluids may be considered shear-thinning. We measured the shear viscosity of the aqueous polymer solutions and obtained values for Carreau shear-thinning fluid model parameters at each polymer concentration. Separately, we measured the average bulk diffusivity for each solution. The estimates of the residual film using penetrating fluid tip and mean velocities were measured as a function of the Peclet (Pe), Reynolds (Re), Carreau (Cu0), and viscous Atwood number based on zero shear-rate viscosity (At0) where the latter two were computed using c0. For Cu0 > 1, we observe a corkscrew type instability where the wavelength increases as diffusion is diminished but requires a finite amount of diffusion to appear.
Numerical investigation of nanosecond pulsed plasma actuators for control of shock-wave/boundary-layer separation
Authors: Kinefuchi Kiyoshi , Starikovskiy Andrey Y. , Miles Richard B.
Published: October 2018

This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced boundary-layer separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: boundary layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the boundary-layer separation stronger, while the canted electrode produced vorticity and suppressed the boundary-layer separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/boundary-layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/boundary-layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the boundary layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the boundary layer and, consequently, mitigating the shock induced boundary layer separation.
Decade of change in Enhalus acoroides seagrass meadows in Guam, Mariana Islands
Authors: LaRoche Carly K. , Goldstein Benjamin R. , Cybulski Jonathan D. , Raymundo Laurie J. , Aoki Lillian R. , Kim Kiho
Published: October 2018

Seagrasses provide important ecosystem services, including carbon sequestration. However, there are significant gaps in our estimates of seagrass coverage, particularly in the western tropical Pacific. In the present study we assessed the status and extent of seagrass meadows, dominated by Enhalus acoroides, around Guam, the largest and most populated island in the Marianas. The combined above- and belowground biomass of E. acoroides (~2300g dry weight m–2) is the highest reported for this species and among the highest for all seagrass species. Elemental analysis of C, N and P revealed variations across site and plant part (i.e. above- v. belowground); N:P ratios suggested N limitation. Between 2004 and 2015, seagrass meadows in Guam decreased in total size by 22%, although it is unclear whether this change was part of a long-term trend and whether it was caused by natural or human factors. The high standing stock of E. acoroides suggests that further examination of this species and this region will be needed to better estimate global seagrass carbon stocks.
Injury and mortality of two Mekong River species exposed to turbulent shear forces
Authors: Colotelo A. H. , Mueller R. P. , Harnish R. A. , Martinez J. J. , Phommavong T. , Phommachanh K. , Thorncraft G. , Baumgartner L. J. , Hubbard J. M. , Rhode B. M. , Deng Z. D.
Published: October 2018

Global hydropower development is one solution proposed to address the increase in energy needs. However, hydropower-related impacts on riverine ecological systems are not well understood. The Mekong River Basin (MRB) is one of the world’s largest waterways and is presently experiencing significant hydropower expansion. It is also one of the most biodiverse rivers; serving as home to many species that are blocked or hindered by the development of dams. One source of injury and mortality for downstream moving fishes is passage through the turbine environment where fishes may be exposed to several physical stressors (e.g. shear forces, rapid decompression, blade strike and turbulence). The current study sought to understand the susceptibility of blue gourami (Trichopodus trichopterus) and iridescent shark (Pangasianodon hypophthalmus) to shear forces. Fishes were exposed to an underwater jet with velocities up to 21.3ms–1 (equating to strain rates of up to 1185s–1) and were assessed for behavioural effects, injuries and mortality. Overall, it was determined that both species were susceptible to the shear forces applied in this study and the effects were more pronounced at higher strain rates. Gouramis were more susceptible than sharks. To minimise impacts on these species, shear forces within turbines should not exceed critical limits.
Influence of follicle size on bovine oocyte lipid composition, follicular metabolic and stress markers, embryo development and blastocyst lipid content
Authors: Annes Kelly , Müller Diego B. , Vilela Jorge A. P. , Valente Roniele S. , Caetano Diana P. , Cibin Francielli W. S. , Milazzotto Marcella P. , Mesquita Fernando S. , Belaz Katia R. A. , Eberlin Marcos N. , Sudano Mateus J.
Published: October 2018

This study assessed the lipid composition of oocytes from different follicle sizes and compared the expression of lipid-related genes and follicular fluid (FF) molecules between groups. We also investigated the functional consequences of differences on embryo development and blastocyst lipid deposits. Oocytes and FF were recovered from different follicle sizes. Oocytes from small (≤5mm) and large (≥6mm) bovine follicles were used to produce Day 7 expanded blastocysts (Day7Ex) and blastocysts that only became expanded at Day 8 (Day8Ex) after insemination. Oocytes from >8mm follicles had the highest lipid content. Few oocyte phospholipid variations were identified between groups. Very long chain fatty acid elongase 6 (ELOVL6) mRNA abundance was reduced in larger follicle-derived oocytes compared with the ≤2mm group. Increased levels of glucose, reactive oxygen species, glutathione and superoxide dismutase activity were also identified in FF from larger follicles. Large follicle-derived embryo development and lipid content of Day7Ex were greater than those derived from small follicles. Day8Ex had greater lipid deposition than Day7Ex. Oocytes and blastocysts exhibited follicle size-specific lipids. Large-follicle oocytes had increased lipid content and became Day7Ex with greater lipid deposition whereas delayed blastocoel expansion associated with a prolonged period of culture determined the lipid accumulation of Day8Ex. The FF microenvironment of large follicles seems to favour embryo development.
Integrative genomic analysis of mouse and human hepatocellular carcinoma
Authors: Dow Michelle , Pyke Rachel M. , Tsui Brian Y. , Alexandrov Ludmil B. , Nakagawa Hayato , Taniguchi Koji , Seki Ekihiro , Harismendy Olivier , Shalapour Shabnam , Karin Michael , Carter Hannah , Font-Burgada Joan
Published: October 2018

Cancer genomics has enabled the exhaustive molecular characterization of tumors and exposed hepatocellular carcinoma (HCC) as among the most complex cancers. This complexity is paralleled by dozens of mouse models that generate histologically similar tumors but have not been systematically validated at the molecular level. Accurate models of the molecular pathogenesis of HCC are essential for biomedical progress; therefore we compared genomic and transcriptomic profiles of four separate mouse models [MUP transgenic, TAK1-knockout, carcinogen-driven diethylnitrosamine (DEN), and Stelic Animal Model (STAM)] with those of 987 HCC patients with distinct etiologies. These four models differed substantially in their mutational load, mutational signatures, affected genes and pathways, and transcriptomes. STAM tumors were most molecularly similar to human HCC, with frequent mutations in
Ctnnb1
, similar pathway alterations, and high transcriptomic similarity to high-grade, proliferative human tumors with poor prognosis. In contrast, TAK1 tumors better reflected the mutational signature of human HCC and were transcriptionally similar to low-grade human tumors. DEN tumors were least similar to human disease and almost universally carried the
Braf
V637E mutation, which is rarely found in human HCC. Immune analysis revealed that strain-specific MHC-I genotype can influence the molecular makeup of murine tumors. Thus, different mouse models of HCC recapitulate distinct aspects of HCC biology, and their use should be adapted to specific questions based on the molecular features provided here.
Noncanonical autophagy at ER exit sites regulates procollagen turnover
Authors: Omari Shakib , Makareeva Elena , Roberts-Pilgrim Anna , Mirigian Lynn , Jarnik Michal , Ott Carolyn , Lippincott-Schwartz Jennifer , Leikin Sergey
Published: October 2018

Significance

Type I collagen, a major component of bone, skin, and other connective tissues, is synthesized in the endoplasmic reticulum (ER) and passes through the secretory pathway. Rerouting of its procollagen precursor to a degradative pathway is crucial for reducing intracellular buildup in pathologies caused by defects in procollagen folding and trafficking. Here, we identify an autophagy pathway initiated at ER exit sites (ERESs). Procollagen proteins following this pathway accumulate at ERESs modified with ubiquitin, LC3, p62, and other autophagy machinery. Modified ERESs carrying procollagen are then engulfed by lysosomes through a microautophagy-like mechanism, not involving conventional, double-membrane autophagosomes. Procollagen homeostasis thus involves a noncanonical mode of autophagy initiated at ERESs, which might also be important in degradation of other secretory proteins.
SOX4 controls invariant NKT cell differentiation by tuning TCR signaling
Authors: Malhotra Nidhi , Qi Yilin , Spidale Nicholas A. , Frascoli Michela , Miu Bing , Cho Okhyun , Sylvia Katelyn , Kang Joonsoo
Published: October 2018

Natural killer T (NKT) cells expressing the invariant T cell receptor (iTCR) serve an essential function in clearance of certain pathogens and have been implicated in autoimmune and allergic diseases. Complex effector programs of these iNKT cells are wired in the thymus, and upon thymic egress, they can respond within hours of antigenic challenges, classifying iNKT cells as innate-like. It has been assumed that the successful rearrangement of the invariant iTCRα chain is the central event in the divergence of immature thymocytes to the NKT cell lineage, but molecular properties that render the iTCR signaling distinct to permit the T cell lineage diversification remain obscure. Here we show that the High Mobility Group (HMG) transcription factor (TF) SOX4 controls the production of iNKT cells by inducing MicroRNA-181 (Mir181) to enhance TCR signaling and Ca2+ fluxes in precursors. These results suggest the existence of tailored, permissive gene circuits in iNKT precursors for innate-like T cell development.
Definable Categorical Equivalence
Authors: Hudetz Laurenz
Published: October 2018

This article proposes to explicate theoretical equivalence by supplementing formal equivalence criteria with preservation conditions concerning interpretation. I argue that both the internal structure of models and choices of morphisms are aspects of formalisms that are relevant when it comes to their interpretation. Hence, a formal criterion suitable for being supplemented with preservation conditions concerning interpretation should take these two aspects into account. The two currently most important criteria—generalized definitional equivalence (Morita equivalence) and categorical equivalence—are not optimal in this respect. I put forward a criterion that takes both aspects into account: the criterion of definable categorical equivalence.