bluuebunny/crossref_metadata_2025 huggingface dataset:
GaiaDR2 reveals a star formation burst in the disc 2–3 Gyr ago
Authors: Mor R. , Robin A. C. , Figueras F. , Roca-Fàbrega S. , Luri X.
Published: March 2019

We useGaiadata release 2 (DR2) magnitudes, colours, and parallaxes for stars withG <  12 to explore a parameter space with 15 dimensions that simultaneously includes the initial mass function (IMF) and a non-parametric star formation history (SFH) for the Galactic disc. This inference is performed by combining the Besançon Galaxy Model fast approximate simulations (BGM FASt) and an approximate Bayesian computation algorithm. We find inGaiaDR2 data an imprint of a star formation burst 2–3 Gyr ago in the Galactic thin disc domain, and a present star formation rate (SFR) of ≈1 M⊙/yr. Our results show a decreasing trend of the SFR from 9–10 Gyr to 6–7 Gyr ago. This is consistent with the cosmological star formation quenching observed at redshiftsz <  1.8. This decreasing trend is followed by a SFR enhancement starting at ∼5 Gyr ago and continuing until ∼1 Gyr ago which is detected with high statistical significance by discarding the null hypothesis of an exponential SFH with ap-value = 0.002. We estimate, from our best fit model, that about 50% of the mass used to generate stars, along the thin disc life, was expended in the period from 5 to 1 Gyr ago. The timescale and the amount of stellar mass generated during the SFR enhancement event lead us to hypothesise that its origin, currently under investigation, is not intrinsic to the disc. Thus, an external perturbation is needed for its explanation. Additionally, for the thin disc we find a slope of the IMF ofα3 ≈ 2 for massesM >  1.53 M⊙andα2 ≈ 1.3 for the mass range between 0.5 and 1.53M⊙. This is the first time that we consider a non-parametric SFH for the thin disc in the Besançon Galaxy Model. This new step, together with the capabilities of theGaiaDR2 parallaxes to break degeneracies between different stellar populations, allow us to better constrain the SFH and the IMF.
Zebra-stripe sources in the double-plasma resonance model of solar radio zebras
Authors: Karlický M. , Yasnov L.
Published: March 2019

Context. Radio bursts with fine structures are used in diagnostics of solar flare plasmas, of which zebra structures are the most important. However, there is still a debate about their origin.

Aims. The most probable model of zebras is that based on double-plasma resonance (DPR) instability. The paper wants to contribute to a verification of this model.

Methods. We used analytical methods.

Results. We studied the DPR model in two scenarios: a model with the zebra-stripe sources in a single loop and a model with the zebra-stripe sources moving through a fan of magnetic field lines. In the first case, we found several new relations among the parameters of zebra stripes and their sources, which can be used to analyze observed zebras and thus to verify if the zebra is generated according to the DPR model. These relations were derived for the zebra-stripe sources distributed along the loop and also for those having some extent in the loop radius. In the scenario with the moving zebra-stripe sources, we determined the parameters of the 14 December 2006 zebra and estimated a change of the ratio of magnetic field and density scales causing the change of zebra-stripe frequencies. In this case we found that this zebra can be also explained in the model with the zebra-stripe sources in a single loop. Both the interpretations are discussed.
Écologie industrielle, écologie territoriale : les jeunes chercheurs s’emparent des questions épistémologiques et d’interdisciplinarité
Authors: Jambou Maël , Herbelin Alice , Chebbi Armel
Published: March 2019

Étroitement liés quant à leurs héritages mais se distinguant sur les questions épistémologiques et ontologiques, les champs de l’écologie industrielle, de l’écologie industrielle et territoriale et de l’écologie territoriale font face à un double enjeu : amorcer des réflexions sur l’interdisciplinarité qui les relie et structurer une communauté de chercheurs francophones. Cet article est une synthèse des interventions et débats qui ont animé les premières rencontres des jeunes chercheurs en écologie industrielle, écologie territoriale et écologie industrielle et territoriale, qui se sont tenues à l’Université de technologie de Troyes, les 13 et 14 avril 2017. Cet évènement a permis de questionner les fondements épistémologiques de ces champs ainsi que l’interdisciplinarité qui en découle, dans la perspective de fédérer un réseau de jeunes chercheurs.
Particularités de la paranoïa sensitive
Authors: Brémaud Nicolas
Published: March 2019

L’auteur se propose de revenir sur ce délire bien particulier qu’est le délire de relation des sensitifs (ou paranoïa sensitive), isolé par Kretschmer en 1918. Si le nom de Kretschmer est assez peu cité dans la littérature, les « caractères » sensitifs mis en avant sont pourtant encore souvent repris dans la description de tableaux cliniques de certaines formes de paranoïa, et nous montrerons ainsi que ce délire est bien d’actualité. Après avoir exposé les grandes lignes de la conception kretschmérienne et donc les particularités de la paranoïa sensitive, nous proposons une courte revue de la littérature, la façon dont ce délire fut reçue dans le champ psychanalytique, et nous proposerons enfin en guise d’ouverture un regard lacanien qui permet à certains égards de rapprocher la paranoïa sensitive de la psychose dite « ordinaire ». Cette forme singulière de paranoïa se révèle bien différente du tableau classique dressé en son temps par Kraepelin, éloigné des délires systématisés et extra-ordinaires de type Schreber. Nous aurions affaire ici à des sujets décrits - avant le déclenchement du délire - comme des sujets sensibles, introvertis, timides, hyperémotifs, intériorisant les affects, réfrénant leurs pulsions, s’auto-dévalorisant, susceptibles, mal assurés dans leur relation à la sexualité, etc. Un événement, une « expérience vécue »(Erlebnis),souvent une remarque, un reproche, un regard, va déclencher le délire, comme la goutte d’eau faisant déborder le vase. Pas d’hallucination, pas de grand délire, mais un délire essentiellement de « relation », avec sentiment de persécution, sentiment surtout d’échec, d’insuffisance et d’humiliation, impression de malveillance de l’entourage, interprétations délirantes de menus faits du quotidien, ressentiment, insécurité, auto-dévalorisation. L’ensemble du tableau se situerait donc sur le plan relationnel. On peut dire de la conception de Kretschmer qu’elle rompt avec les conceptions déficitaires; en ce sens on peut la qualifier de psychodynamique. Nous verrons combien les descriptions fines qui ont été faites de ce tableau clinique sont dans le fond assez fréquemment rencontrées en pratique et qu’elles nous poussent à repenser le cadre de la paranoïa.
Neurovascular anatomy around the knee: Relevance of the dangers of self-drilling external fixator pin tips
Authors: Reipond Lucy , Trompeter Alex , Szarko Matthew
Published: March 2019

Introduction: With external fixation of the femur and tibia, iatrogenic injury to neurovasculature from self-drilling tips of fixation pins is an important consideration in pin placement. Precise knowledge of the neurovascular anatomy in the distal femur and proximal tibia is important to limit potential pin misplacement.

Method: Six pin placement sites on six cadaveric legs were used in accordance with current placement techniques. After pin placement, the soft tissue around each pin was dissected and the distances between the pin tips and the surrounding neurovasculature were measured.

Results: The resultant data allow for a description of safe and unsafe corridors which can be used for external fixator pin placement. Safe sagittal insertion into the distal femur should consist of two pins: (1) 90 mm ± proximal from the proximal pole of the patella and 3 mm ± medially, (2) 55 mm ± proximal from the proximal pole of the patella and 2 mm ± laterally. Safe coronal insertion into the distal femur should consist of two pins: (1) 30 mm ± proximal to the lateral epicondyle, (2) 100 mm ± proximal to the lateral epicondyle. Safe proximal tibial pin placement should consist of two pins and be placed at an oblique angle: (1) 20 mm ± distal to the tibial tuberosity and 2 mm ± medially, (2) 55 mm ± distal to the tibial tuberosity and 2 mm ± medially.

Discussion: This study forms an investigation into the safe areas for placement of external fixator pins, within the distal femur and proximal tibia, specifically, detailing the best practice for pin placement in relation to the tips of the external fixation pins.
An innovative laparoscopic and endoscopic technique in an animal model: combined gastric full-thickness tumor resection
Authors: Morita Flavio , Sakai Christiano , Kawamoto Flavio , de Moura Eduardo , Sakai Paulo
Published: March 2019

Background and study aims The combination of endoscopy with laparoscopy for full-thickness gastric resection has received much attention. The advantage in using it is removak of the target lesion without resection of excessive normal tissue. The technique could prevent deformed scars, particularly at the cardia and in the prepyloric area. The aim of this protocol was to evaluate a new combined operation for full-thickness resection of the gastric wall.

Materials and methods Gastric subepithelial lesions in multiple topographic locations of the stomach were simulated in seven live pigs. Full-thickness gastric resection was undertaken and after assessment of the outcome, the animals were euthanized. The primary endpoint was accomplishment of the procedure following all steps in the new technique, in various gastric locations. The secondary endpoints were duration of the procedure, quality of specimen margins, and complications.

Results Resections were successful, complete, and complication-free, ensuring a safe surgical margin of healthy tissue. The procedure was completed in 50 minutes. No mucosal perforation or gas escape occurred.

Conclusions The combined technique was safe, effective and minimally invasive. No expensive materials were used. Lesion exposure, gastric content leakage, incomplete resection, and excessive normal tissue elimination were avoided. Human trials of this technique may be warranted.
Long Term Effects of Behavioural Interventions to Increase Exercise Among Breast Cancer Patients After Medical Rehabilitation: secondary Analysis of a Randomized Controlled Trial
Authors: Exner Anne-Kathrin , Kähnert Heike , Sauzet Odile , Leibbrand Birgit , Berg-Beckhoff Gabriele
Published: March 2019

Purpose Physical activity (PA) as secondary prevention for breast cancer patients has many positive effects. To evaluate the effectiveness of an intervention involving behavioural and volitional strategies to increase exercise.

Materials and Methods The study designed as a randomized controlled trail with 2 follow-up (6 and 12 months after rehabilitation). 1,143 participants were randomized to one of the 4 study groups. Group differences were analysed by multi-level-models.

Results After rehab, patients with the combined modules, aftercare-planning (AP) and telephone-support (TS), did exercise 69 min per week (95% CI: 42.85; 94.90) more than the control group. Inactive patients at the beginning of the rehabilitation benefit from the combined intervention. The phone-based intervention alone did not show any effect.

Discussion and Conclusion Rehab with the AP module combined with the TS module is associated with patients undertaking more PA.
Rektumkarzinom
Authors: Kretzschmar Alexander
Published: March 2019

Ist eine Watch-and-Wait-Strategie (WW) bei Patienten mit einem Rektumkarzinom mit einer klinischen kompletten Response (cCR) nach einer neoadjuvanten Therapie eine geeignete Alternative zu einer totalen mesorektalen Exzision (TME) als standardisiertem chirurgischem Operationsverfahren? Diese Frage wird seit Jahren diskutiert. Eine neue retrospektive Fallserie von Patienten des Memorial Sloan Kettering Cancer Center in New York/USA (MSKCC) kann die Vorbehalte nicht ausräumen.
Kleinzelliges Bronchialkarzinom
Authors: Krome Susanne
Published: March 2019

Im extensiven Stadium kleinzelliger Bronchialkarzinome (SCLC) sind Remissionen nach einer platinbasierten Chemotherapie selten dauerhaft. Immuntherapien als Ergänzung oder Erhaltung blieben bislang hinter den Erwartungen zurück. Der monoklonale Antikörper Atezolizumab verlängerte nun in der Phase-III-Studie IMpower133 das progressionsfreie Überleben (PFS) und das Gesamtüberleben (OS).
SABCS 2018
Authors: Ortner Petra
Published: March 2019

Naturgemäß stand beim 41. San Antonio Breast Cancer Symposium vom 4. bis 8. Dezember die aktive Brustkrebstherapie im Vordergrund. Es wurden wichtige Therapiestudien vorgestellt, die die Behandlung des Mammakarzinoms verändern werden. Doch auch den Themen Survivorship Care und Supportivtherapie wurde ein breiter Raum gegeben, denn es hat sich über viele Studien hinweg gezeigt, dass optimierte supportive Maßnahmen zur Therapieadhärenz beitragen und ein gesunder Lebensstil Einfluss auf das Überleben besitzt.
Feasibility and safety of third-space endoscopic full-thickness resection in ex vivo and in vivo porcine models
Authors: Goto Osamu , Sasaki Motoki , Akimoto Teppei , Tatsuguchi Atsushi , Kaise Mitsuru , Iwakiri Katsuhiko , Yahagi Naohisa
Published: March 2019

Background and study aims Endoscopic full-thickness resection (EFTR) involves several technical issues that need to be addressed. We devised a novel technique termed third-space EFTR and investigated its feasibility and safety in animal models.

Methods Third-space EFTR was performed in three isolated porcine stomachs (ex vivo) and four live pigs (in vivo, 1-week survival). The technique involved a circumferential mucosal incision, submucosal tunnelling on the proximal side, endoscopic suturing of the surrounding mucosa, a circumferential seromuscular incision in the submucosal tunnel, transoral retrieval and entry site closure of the tunnel. The technical outcomes were investigated.

Results In the ex vivo study, the procedure was successfully completed with R0 resection. In the in vivo study, the procedure was completed in all pigs; however, R0 resection failed in one pig owing to snaring resection. All pigs survived without severe adverse events.

Conclusions Our findings indicate that third-space EFTR is feasible and safe. This technique may be useful as a minimally invasive endoscopic option for reliable treatment of small gastric submucosal tumours.
Commercial Pharmacogenetic Tests in Psychiatry: Do they Facilitate
the Implementation of Pharmacogenetic Dosing Guidelines?
Authors: Fan Mikayla , Bousman Chad A.
Published: March 2019

Introduction Expert groups have created dosing guidelines to
facilitate the implementation of pharmacogenetic knowledge into clinical
practice and commercial pharmacogenetic tests are becoming increasingly
accessible. However, the extent to which these commercial tests facilitate
the implementation of dosing guidelines is not clear.

Methods Gene-drug pairs included on 22 commercial pharmacogenetic
test panels were extracted and cross-referenced with the 74 gene-drug pairs
with dosing guidelines in the Pharmacogenetics Knowledgebase, with
particular attention given to the 28 gene-drug pairs relevant to
psychiatry.

Results On average, 70% of the 28 gene-drug pairs most
relevant to psychiatry were covered by the examined tests. Six gene-drug
pairs (CYP2D6-venlafaxine, CYP2D6-paroxetine,
CYP2D6-amitriptyline, CYP2C19-sertraline,
CYP2C19-citalopram, CYP2C19-amitriptyline) were included by
all tests. Gene-drug pairs included on less than half of the test panels
included HLA-B-phenytoin (14%), HLA-A-carbamazepine
(24%), HLA-B-carbamazepine (29%), and
CYP2D6-zuclopenthixol (43%).

Discussion Most commercial pharmacogenetic tests we examined are
well-equipped to facilitate implementation of the majority of dosing
guidelines relevant to psychiatry but are limited in their ability to
facilitate implementation of the full spectrum of dosing guidelines
currently available.
Non-Vitamin K Oral Anticoagulants in Comparison to Phenprocoumon in Geriatric and Non-Geriatric Patients with Non-Valvular Atrial Fibrillation
Authors: Hohmann Christopher , Hohnloser Stefan H. , Jacob Josephine , Walker Jochen , Baldus Stephan , Pfister Roman
Published: March 2019

Geriatric characteristics such as high age, multi-morbidity, polypharmacy and frailty are common in patients with atrial fibrillation (AF). In a retrospective study using a German claims database, effectiveness (ischaemic stroke/systemic embolism) and safety (intracerebral, gastrointestinal and major extracranial bleeding) were compared in patients with non-valvular AF starting non-vitamin K oral antagonists (NOACs) (apixaban, dabigatran and rivaroxaban) and phenprocoumon. Cox proportional hazards models were used to calculate adjusted hazard ratios, and interaction terms of the treatment group and geriatric status (defined by age ≥75 years, frailty, ≥ 4 co-morbidities and polypharmacy) were entered into the model. A total of 42,562 and 27,939 patients initiated NOAC and phenprocoumon treatment (mean age 74 years ± 11, 51% male) with a follow-up time of 147,785 person-years. Note that 52.9% of patients were elderly, 50.8% were frail, 37.0% were co-morbid and 46.5% had polypharmacy. NOAC use was not associated with effectiveness and gastrointestinal bleeding, neither in geriatric nor in non-geriatric patients. The hazard of major extracranial and intracranial bleeding was significantly decreased for NOAC use, with similar risk reduction in geriatric and non-geriatric patients: major extracranial bleeding 0.70 (95% confidence interval [CI], 0.56–0.87) to 0.73 (95% CI, 0.60–0.89) for the geriatric groups and 0.71 (95% CI, 0.56–0.93) to 0.76 (0.59–0.98) for the non-geriatric groups (p-values for interaction > 0.6); and intracranial bleeding 0.52 (95% CI, 0.39–0.69) to 0.59 (95% CI, 0.47–0.73) for the geriatric groups and 0.54 (95% CI, 0.37–0.79) to 0.65 (95% CI, 0.49–0.86) for the non-geriatric groups (p-values for interaction > 0.2). Hence, NOACs showed similar effectiveness and superior safety in geriatric and non-geriatric patients.
Tracheoscopic Findings and Their Impact on Respiratory Symptoms in Children with Esophageal Atresia
Authors: Balleisen Johannes , Holzki Josef , Cernaianu Grigore , Alejandre Alcàzar Miguel , Dübbers Martin , Fischer Janina
Published: March 2019

Introduction Esophageal atresia (EA) is often accompanied by tracheobronchial malformations leading to stridor, recurrent bronchitis, and occasionally to life-threatening obstructive apnea after surgical repair. The aim of this study was to identify the presence of tracheomalacia in patients with EA and tracheoesophageal fistula (TEF) pre- and postoperatively and to find endoscopic correlates leading to clinical airway symptoms.

Methods In a cohort of 362 patients with EA-TEF who underwent 595 tracheoscopies at the Children's Hospital of Cologne between January 1983 and December 2002, impaired tracheal lumen, localization of TEF, tracheal pulsations, and corresponding clinical symptoms were retrospectively analyzed.

Results The incidence of tracheomalacia was higher in patients with EA and TEF (Gross B–D) compared with patients with EA alone (Gross A) and average tracheal collapse does not significantly change before and after surgical repair of the esophagus in all types. Patients with cyanosis while eating and obstructive apnea presented with an average tracheal collapse of 89%. The presence of respiratory symptoms such as cough, stridor, or bronchitis was not associated with a higher grade of tracheal collapse compared with patients without any airway symptoms (average tracheal collapse of 37% in symptomatic patients vs. 33% in nonsymptomatic patients).

Conclusion Tracheomalacia tends to be present independently of surgical procedure. Tracheomalacia should be measured by tracheoscopy (in % of tracheal collapse). Patients with a tracheal collapse of >80%, a ventral pulsation, and obstructive apnea or cyanosis in combination, are at risk for life-threatening situations and further surgical treatment should be considered.
Behandlung von Spenderreaktionen bei präparativen Hämapheresen
Authors: Martens Jörg , Heuft Hans-Gert
Published: March 2019

Präparative Hämapheresen sind in vielen transfusionsmedizinischen Einrichtungen Standardverfahren zur modernen Herstellung von Blutprodukten. Sie kommen jährlich weltweit millionenfach zum Einsatz. Spenderreaktionen im Rahmen von präparativen Hämapheresen bei gesunden unverwandten Spendern sind dank moderner Apheresetechnik und hohen Prozessstandards heute ganz überwiegend als mild und klinisch nicht signifikant einzustufen. Die Kenntnis dieser, aber auch der seltenen schwerwiegenden Reaktionen, ihrer Symptome und ihrer Behandlung ist wichtig, um Spendersicherheit und Spendercompliance zu gewährleisten und Verfahrensabbrüche zu reduzieren bzw. zu vermeiden.
Denoising of surface electromyogram based on complementary ensemble empirical mode decomposition and improved interval thresholding
Authors: Xi Xugang , Zhang Yan , Zhao Yunbo , She Qingshan , Luo Zhizeng
Published: March 2019

Surface electromyogram (sEMG) signals are physiological signals that are widely applied in certain fields. However, sEMG signals are frequently corrupted by noise, which can lead to catastrophic consequences. A novel scheme based on complementary ensemble empirical mode decomposition (CEEMD), improved interval thresholding (IT), and component correlation analysis is developed in this study to reduce noise contamination. To solve the problem of losing desired information from sEMG, an sEMG signal is first decomposed using CEEMD to obtain intrinsic mode functions (IMFs). Subsequently, IMFs are selected via component correlation analysis, which is a measure used to select relevant modes. Thus, each selected IMF is modified through improved IT. Finally, the sEMG signal is reconstructed using the processed and residual IMFs. Root-mean-square error (RMSE) and signal-to-noise ratio (SNR) are introduced as evaluation criteria for the sEMG signal from the standard database. With SNR varying from 1 dB to 25 dB, the proposed method increases SNR by at least 1 dB and reduces RMSE compared with stationary wavelet transform and other denoising algorithms based on empirical mode decomposition. Moreover, the proposed method is applied to hand motion recognition. Results show that the rate of the denoised sEMG signal is higher than that of the raw sEMG signal.
Comparative study of surface modification of polyethylene by parallel-field and cross-field atmospheric pressure plasma jets
Authors: Liu Xin , Wang Chuanchuan , Liu Jiyu , Wang Guansong , Yang Zhikang , Chen Faze , Song Jinlong
Published: March 2019

Atmospheric pressure plasma jets (APPJs), which can be roughly classified as parallel-field APPJ and cross-field APPJ based on the direction of gas flow and electrical field, have been widely used for surface modification of polymers, but the modification difference between the two kinds of APPJ remains unknown. In this paper, the surface modification of polyethylene (PE) sheet by the two types of APPJ is comparatively studied. Results show that the two types of APPJ can improve the surface wettability of the PE sheet obviously through the comprehensive effect including plasma etching and inducing of hydrophilic groups. However, some differences are also observed. Compared with the cross-field APPJ, the etching effect induced by the parallel-field APPJ is more obvious under the same treatment condition. Additionally, the concentration of active species induced by the cross-field APPJ is higher than that of the parallel-field APPJ at the upstream region. By contrast, at the downstream region, the concentration of active substances induced by the parallel-field APPJ is higher. Finally, the bonding experiment shows that both plasma treatments can improve the bonding properties of PE surfaces, but the adhesion force improved by the parallel-field APPJ is always higher than that of the cross-field APPJ under the same parameters, which is attributed to the more remarkable etching effect that produces a large number of nano-grooves, thus increasing the contact area between UV glue and PE surfaces.
Modulation of adhesion microenvironment using mesh substrates triggers self-organization and primordial germ cell-like differentiation in mouse ES cells
Authors: Ando Yuta , Okeyo Kennedy Omondi , Adachi Taiji
Published: March 2019

The cell adhesion microenvironment plays contributory roles in the induction of self-organized tissue formation and differentiation of pluripotent stem cells (PSCs). However, physical factors emanating from the adhesion microenvironment have been less investigated largely in part due to overreliance on biochemical approaches utilizing cytokines to drive in vitro developmental processes. Here, we report that a mesh culture technique can potentially induce mouse embryonic stem cells (mESCs) to self-organize and differentiate into cells expressing key signatures of primordial germ cells (PGCs) even with pluripotency maintained in the culture medium. Intriguingly, mESCs cultured on mesh substrates consisting of thin (5 μm-wide) strands and considerably large (200 μm-wide) openings which were set suspended in order to minimize the cell-substrate adhesion area, self-organized into cell sheets relying solely on cell-cell interactions to fill the large mesh openings by Day 2, and further into dome-shaped features around Day 6. Characterization using microarray analysis and immunofluorescence microscopy revealed that sheet-forming cells exhibited differential gene expressions related to PGCs as early as Day 2, but not other lineages such as epiblast, primitive endoderm, and trophectoderm, implying that the initial interaction with the mesh microenvironment and subsequent self-organization into cells sheets might have triggered PGC-like differentiation to occur differently from the previously reported pathway via epiblast-like differentiation. Overall, considering that the observed differentiation occurred without addition of known biochemical inducers, this study highlights that bioengineering techniques for modulating the adhesion microenvironment alone can be harnessed to coax PSCs to self-organize and differentiate, in this case, to a PGC-like state.
Evidence of resistive switching into a dynamical state in antiferromagnetic iridates
Authors: Williamson Morgan , Shen Shida , Cao Gang , Zhou Jianshi , Tsoi Maxim
Published: March 2019

We investigate the electrically-driven switching between low and high resistance states in antiferromagnetic Sr3Ir2O7 single crystals. We demonstrate that the switching state at high electrical biases displays an increased noise pattern, which is indicative of a dynamical state at high biases. We employ a spectrum analyzer to characterize the noise pattern associated with the high-bias switching state and investigate the dependence of the noise spectrum on the magnitude of applied bias and magnetic field. The emergence of the noise was found to be strongly correlated with the onset of resistive switching. The noise power density displayed a 1/f2 frequency dependence with an amplitude mimicking the hysteretic behavior of the resistance switching. We argue that the observed noise spectrum could be associated with a random switching between different states at high biases and discuss various interpretations of its origin including random telegraph signal (RTS) and red noises.
A simplified and versatile calibration method for multi-camera optical systems in 3D particle imaging
Authors: Machicoane N. , Aliseda A. , Volk R. , Bourgoin M.
Published: March 2019

This article describes a stereoscopic multi-camera calibration method that does not require any optical model. It is based on a measure of the light propagation within the measurement volume only instead of modeling its entire path up to the sensors. The calibration uses simple plane by plane transformations which allow us to directly link pixel coordinates to light rays. The appeal of the proposed method relies on the combination of its simplicity of implementation (it is particularly easy to apply in any sophisticated optical imaging setup), its versatility (it can easily handle index-of-refraction gradients, as well as complex optical arrangements), and its accuracy {we show that the proposed method gives better accuracy than commonly used techniques, based on Tsai’s simple pinhole camera model [R. Tsai, J. Rob. Autom. 3, 323 (1987)], while its numerical implementation remains extremely simple}. Based on ideas that have been available in the fluid mechanics community, this method is a compact turn-key algorithm that can be implemented with open-source routines.
Emission in the ion cyclotron range of frequencies (ICE) on NSTX and NSTX-U
Authors: Fredrickson E. D. , Gorelenkov N. N. , Bell R. E. , Diallo A. , LeBlanc B. P. , Podestà M. ,   NSTX Team
Published: March 2019

We report here on observations of magnetic fluctuations in the ion-cyclotron frequency range on NSTX and NSTX-U. In many respects, the fluctuations appear similar to the ion cyclotron emission (ICE) seen in conventional tokamaks. However, a significant difference between previous observations of ICE and the ICE on NSTX is that the frequency of ICE in conventional tokamaks is typically near the ion cyclotron frequency of the energetic fast ions at the plasma edge. In NSTX and NSTX-U, the magnetic fluctuation frequency corresponds to the ion cyclotron frequency deeper in the plasma, near the location of an internal transport barrier. As on conventional tokamaks, higher harmonics of the deuterium cyclotron frequency, as high as the seventh, are seen with the strongest signal sometimes from higher harmonics. The emission usually appears as an irregular sequence of short bursts typically ≤100 μs in duration although nearly continuous emission for several ms has also been seen under some conditions. Measurements of the emission with a toroidal array of fast probes show that the emission is a long wavelength, spatially coherent mode. The emission frequency does not follow an Alfvénic scaling with density, as seen for compressional Alfvén eigenmodes, but does show a linear scaling with local magnetic field strength. The measured emission shows a compressional polarization consistent with a compressional Alfvén wave. No correlation between the neutron rate and the ICE amplitude is seen. Three-wave coupling between the instability responsible for the ICE and lower frequency modes has also been observed.
Dynamic behavior of water drops impacting on cylindrical superhydrophobic surfaces
Authors: Zhang Haixiang , Yi Xian , Du Yanxia , Zhang Rui , Zhang Xiwen , He Feng , Niu Fenglei , Hao Pengfei
Published: March 2019

This paper investigates the impact behavior between water drops with different velocities and cylindrical superhydrophobic surfaces with various diameters and presents two possible outcomes of drop impact, which are asymmetric rebound and stretched breakup. Due to the special cylindrical topology of the surface, drops undergo an asymmetric spreading and retracting process in the azimuthal and the axial direction, which results in three types of asymmetric rebound, including jug-like rebound, wing-like rebound, and rebound breakup. The stretched breakup is observed in the collision of drops with higher impact velocities and smaller cylinder diameters. The diameter ratio D* and Weber number We are found to be the determinants of the bouncing patterns. With the decrease in the diameter ratio D* or the increase in the Weber number We, the bouncing patterns transformed from jug-like rebound through wing-like rebound and finally to stretched breakup. We put forward a modification form of the Weber number (α = We/D*) affected by the diameter ratio D*, indicating the ratio between the inertia force and the surface tension, as the criterion to distinguish the upward rebound from the downward stretch, which helps obtain the linear relation of critical Wecr and D*cr. Furthermore, asymmetric rebound and stretched breakup could effectively shorten the contact time between drops and substrates. The contact time is found to be mainly determined by the dimensionless parameter α. The correlation between the dimensionless contact time and the dimensionless parameter α is demonstrated to be τc ∝ αn.
Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion
Authors: Mito Masaki , Kitamura Yuichiro , Tajiri Takayuki , Nakamura Kazuma , Shiraishi Ryo , Ogata Kazuma , Deguchi Hiroyuki , Yamaguchi Tomiko , Takeshita Nao , Nishizaki Terukazu , Edalati Kaveh , Horita Zenji
Published: March 2019

We study the effects of hydrostatic pressure (HP) compression on the superconducting transition of severely strained Nb samples, whose grain sizes are reduced to the submicrometer level. Engineered granularity by high-pressure torsion (HPT) treatment changes the strength of coupling between submicrometer-scale grains and introduces lattice strain. We attempt to utilize the initially accumulated shear strain in the starting material for increasing the superconducting transition temperature Tc under HP compression. The HP effects on non-strained Nb have already been investigated in the pressure regime over 100 GPa by Struzhkin et al. [Phys. Rev. Lett. 79, 4262 (1997)], and Tc reportedly exhibited an increase from 9.2 to 9.9 K at approximately 10 GPa. (1) Slightly strained Nb in the HPT treatment exhibits the increase in Tc under HP due to the strengthening of the intergrain coupling, so the pressure scale of the pressure response observed by Struzhkin et al. is reduced to approximately one-seventh at the maximum. (2) Prominently strained Nb in the HPT treatment exhibits the increase in Tc under HP due to a reduction in structural symmetry at the unit-cell level: In a Nb sample subjected to HPT (6 GPa, 10 revolutions), Tc exceeds 9.9 K at approximately 2 GPa. According to our first-principle calculations, the reduction in the structural symmetry affords an increase in the density of states at the Fermi energy, thereby yielding a prominent increase in Tc at low pressures.
Phase-field simulations of surface charge-induced polarization switching
Authors: Liu Di , Zhao Ru , Jafri Hasnain Mehdi , Wang Junsheng , Huang Houbing
Published: March 2019

Understanding and controlling surface charge-induced polarization switching have attracted interest of researchers extensively, and the rich physical interactions between ionic and atomic displacements play a significant role in polarization reversal. In this work, we investigated the mechanism of surface charge-induced polarization switching in PbZr0.2Ti0.8O3 and BiFeO3 thin films by phase-field simulations. We observed ferroelectric polarization reversal by applying positive/negative charge on the top of a thin film, because the double well of free energy becomes asymmetric by applying surface charge. It is found that the nucleation of switching always starts from the surface and gradually expands into the whole film. In BiFeO3 thin films, the formation of an anti-vortex domain provides topological protection for hindering surface charge-induced polarization switching. The present study, therefore, contributes to a better understanding of charge-induced polarization switching and provides guidance for the experimental design of reversible electronic devices by selecting the appropriate polarity region.
On the relevance of electrostatic interactions for the structural relaxation of ionic liquids: A molecular dynamics simulation study
Authors: Pal Tamisra , Vogel Michael
Published: March 2019

We perform molecular dynamics simulations to investigate the structural (α) relaxation of models of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) room temperature ionic liquids. To determine the relevance of electrostatic interactions for the dynamical properties, we systematically scale the partial charges of the ions. Observing the structural relaxation of these charge-scaled ionic liquids from high temperature far above the melting point to low temperatures in the viscous regime, we find that the α-relaxation times τq strongly depend on the strength of the electrostatic interactions. The glassy slowdown τq(T) of all systems is successfully described by splitting the apparent activation energies E(T) into a temperature-independent contribution E∞, which characterizes the α relaxation of the high-temperature liquid, and a temperature-dependent contribution Ec(T), which describes the growing cooperativity and increases exponentially upon cooling. For all used partial charges, we find a common relation between the activation energy E∞ and the glass transition temperature Tg, indicating a close link between simple-liquid and viscous-liquid dynamics. To ascertain the origin of the increase of the cooperative contribution Ec(T), we characterize the evolution of space-time characteristics of dynamical heterogeneities upon cooling. It turns out that the length and time scales of spatially heterogeneous dynamics are the same for all studied charge-scaled ionic liquids when plotted as function of τq. Moreover, we find a common relation between Ec and the size of transient clusters of highly mobile ions.
First-principles assessment of thermoelectric properties of CuFeS2
Authors: Park Junsoo , Xia Yi , Ozoliņš Vidvuds
Published: March 2019

Composed of inexpensive and naturally abundant elements, the chalcopyrite mineral CuFeS2 has received attention as a potentially useful thermoelectric. We use first-principles electronic structure and Boltzmann transport theory calculations to investigate thermoelectric properties of n-doped CuFeS2. We find that energy-dependent carrier lifetimes that are inversely proportional to the electronic density-of-states are crucial for reproducing experimental data on the transport properties, including the measured values of the Seebeck coefficient, α. The heavy-effective-mass conduction band promotes high values of α, but it also leads to low mobility due to strong electron-acoustic-phonon scattering. Low mobility forces one to rely on high carrier concentration to achieve high conductivity, which decreases α and limits the achievable power factor. Our calculations predict that ideally doped CuFeS2 that has been nanostructured to an average grain size d≈20nm can attain thermoelectric figures of merit zT=0.25 to 0.8 for T=300 to 700 K, respectively, due to a reduction in the lattice thermal conductivity.
Strong pinning in the hole-doped pnictide superconductor La0.34Na0.66Fe2As2
Authors: Sundar Shyam , Salem-Sugui S. , Alvarenga A. D. , Doria M. M. , Gu Yanhong , Li Shiliang , Luo Huiqian , Ghivelder L.
Published: March 2019

We present magnetization studies as a function of time, temperature, and magnetic field for H ∥ c-axis, in a hole-doped pnictide superconductor, La0.34Na0.66Fe2As2, with Tc≈27K. The obtained vortex phase-diagram shows that the magnetic irreversibility line is very close to the mean-field superconducting transition line, similar to the low Tc superconductors, evidencing a strong pinning behavior. The irreversibility line does not follow a power law behavior with (Tc−T); however, it is well described using an expression developed in the literature, considering the effect of disorder in the system. The critical current density estimated using the Bean critical-state model is found to be of the order of 105A/cm2 below 12 K in the limit of zero magnetic field. A plot of the normalized pinning force density as a function of the reduced magnetic field at different temperatures shows good scaling, and the analysis suggests that the vortex pinning is due to normal point-like pinning centers. The temperature dependence of the critical current density suggests that the pinning due to the variation in the charge carrier mean free path alone is not sufficient to explain the experimental data. The magnetic relaxation rate as a function of temperature and magnetic field is also studied.
Solid-phase crystallization of densified amorphous GeSn leading to high hole mobility (540 cm2/V s)
Authors: Moto K. , Saitoh N. , Yoshizawa N. , Suemasu T. , Toko K.
Published: March 2019

Improving carrier mobility of polycrystalline Ge films by incorporating Sn is a topic recently attracting a great deal of attention. Here, we substantially update the maximum hole mobility of the polycrystalline GeSn film formed on insulators. In the solid-phase crystallization (SPC) of densified amorphous GeSn on glass, the initial Sn concentration xi (<0.05), film thickness t (40–200 nm), and growth temperature Tanneal (<500 °C) strongly influence the grain size and electrical properties of the resulting GeSn layer. The best characteristics are obtained for xi = 1.6%, which is the largest xi that allows Sn fully substituted in the SPC-GeSn. Reflecting the balance between grain boundary scattering, impurity scattering, and interfacial scattering, the hole mobility is maximized to 420 cm2/V s at t = 150 nm and Tanneal = 475 °C. Moreover, post annealing at 500 °C is effective in reducing defect-induced acceptors and then impurity scattering, especially for Tanneal = 375 °C. This results in a hole mobility as high as 540 cm2/V s.
Native point defects and carbon clusters in 4H-SiC: A hybrid functional study
Authors: Kobayashi Takuma , Harada Kou , Kumagai Yu , Oba Fumiyasu , Matsushita Yu-ichiro
Published: March 2019

We report first-principles calculations that clarify the formation energies and charge transition levels of native point defects and carbon clusters in the 4H polytype of silicon carbide (4H-SiC) under a carbon-rich condition. We applied a hybrid functional that reproduces the experimental bandgap of SiC well and offers reliable defect properties. For point defects, we investigated single vacancies, antisites, and interstitials of Si and C on relevant sites. For carbon clusters, we systematically introduced two additional C atoms into the perfect 4H-SiC lattice with and without removing Si atoms and performed structural optimization to identify stable defect configurations. We found that neutral Si antisites are energetically favorable among Si-point defects in a wide range of the Fermi level position around the intrinsic regime, whereas negatively-charged Si vacancies and a positively-charged Si interstitial on a site surrounded by six Si and four C atoms become favorable under n- and p-type conditions, respectively. For C-point defects, neutral C antisites are favorable under intrinsic and n-type conditions, whereas positively-charged C vacancies become favorable under p-type conditions. We also found that a di-carbon antisite is more favorable than a C-split interstitial, which is the most stable form of single C interstitials.
Computational design of a high-efficiency accelerator grid for a miniature ion thruster by full-aperture ion optics simulations
Authors: Nakano M. , Nakamura K. , Naito Y. , Nakagawa Y. , Takao Y. , Koizumi H.
Published: March 2019

Full-aperture ion optics simulations have been conducted for the inhomogeneous plasma source of a miniature ion propulsion system (MIPS) to design a high-efficiency accelerator grid that provides high degree of the neutral confinement and absence of direct ion impingement. The designed accelerator grid has flat upstream and smoothly curved downstream surfaces with straight holes for easy low-cost manufacture. The diameter of the accelerator aperture was changed from the nominal value of 0.40 mm to 0.25 mm, which decreased neutral leakage and increased the propellant utilization efficiency from 31 to 50%. The direct impingement of ions caused by decreasing the accelerator aperture diameter was compensated by reducing the thickness of the accelerator grid while taking into account the inhomogeneous ion beam current density profile of the MIPS. An off-design performance simulation was conducted to validate the proposed grid design; the obtained results showed that the ion beam could be accelerated smoothly even during throttling the beam current between 75 and 150%. A grid wear simulation was also performed to compare the changes in the propellant utilization efficiency between the nominal and high-efficiency grids caused by erosion. It was found that the propellant utilization efficiency of the high-efficiency grid was greater than that of the nominal grid within the first 5,000 h of operation and that its lifetime exceeded 10,000 h of the accumulated operation time. By using the proposed high-efficiency accelerator grid and MIPS plasma source, the propellant utilization efficiency was increased, while the accelerator impingement current became negligible.
Non-French lexicon in Guianese French Creole
Authors: Wiesinger Evelyn
Published: March 2019

Guianese French Creole1(GFC) is one of the least studied French Creoles, which is especially true with respect to its non-French-related input. Combining sociohistorical, demographic and linguistic data, this contribution gives a first lexico-etymological account of the GFC lexicon of non-French origin, including Amerindian and Portuguese influences and especially the quantitative and qualitative nature of the contribution made by different Niger-Congo languages. These findings are discussed in light of controversial hypotheses on the particular influence of early numerical and/or socially dominant ethnolinguistic groups on the creole lexicon (i.e.Baker 2012), as well as with regard to word classes and semantic domains to which the different groups contributed. Whereas Gbe and non-Gbe languages clearly diverge with regard to their semantic contribution, the early dominance of presumably Gbe-speaking slaves in French Guiana is not reflected in the numerical proportion of Gbe-related lexical items in GFC, at least on the basis of my still limited data. This study thus tentatively confirms the lesser explanatory power of the lexicon for creole genesis scenarios and points to the fact that sub- or adstrate-related lexical items may have taken very complex etymological routes, which clearly need further study.
Attitudes toward EMI in East Asia and the Gulf
Authors: Graham Keith M. , Eslami Zohreh R.
Published: March 2019

In order to raise global profiles of universities, governments around the world have pushed universities to offer English medium instruction (EMI) courses. While research examining the attitudes toward EMI has been conducted in various countries, these studies generally look at a single university and rarely examine attitudes between countries or regions. In order to investigate attitudes from a macro perspective, this study used a systematic literature review method to synthesize findings on attitudes toward EMI in East Asia and the Gulf. The review was guided by the following research questions: (1) What are the attitudes toward EMI in countries in the Gulf and East Asia? and (2) What are the similarities/differences between countries and what factors can be attributed to these? Attitude scores were calculated for twenty studies from ten countries, and the studies were coded by common themes affecting EMI attitudes. Results show that factors affecting attitudes include language and content issues, choice of medium of instruction, instructor quality, motivation to learn English, and deficit views of the L1. As a result of the findings, it is suggested that governments and universities review their EMI policies in order to ensure education quality and maintain the status of local languages.