bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a Combined Explicit–Implicit Approach to Teach Grammatical Forms to Children With Grammatical Weaknesses
Authors: Finestack Lizbeth , Engman Jennifer , Huang Timothy , Bangert Katherine J. , Bader Kaela
Published: November 2019

Purpose

Many children with developmental disorders experience difficulty mastering grammatical forms, including children with developmental language disorder and a subset of children with autism spectrum disorder (ASD). One of the key language features in both of these populations is a weakness in the expressive use of grammatical forms. There is a paucity of studies that evaluate the effectiveness of interventions targeting grammatical forms for populations other than developmental language disorder. The current study evaluated a combined explicit–implicit intervention approach to teach grammatical forms to children with ASD symptomology.

Method

Researchers used a single-subject, nonconcurrent multiple baseline, A-B-C study design. Three children with characteristics of ASD (2 with formal diagnoses) between the ages of 5 and 9 years participated in treatment targeting a weak grammatical structure. After baseline, each participant completed a series of treatment sessions that comprised implicit instruction, followed by a series of treatment sessions that incorporated explicit instruction. Accuracy of use was assessed during each session across baseline, implicit-only, and explicit–implicit conditions as well as 1 week, 1 month, and 2 months posttreatment.

Results

All participants produced target forms with low accuracy across baseline and implicit-only treatment sessions. Within three explicit–implicit treatment sessions, all participants demonstrated a marked increase in level and upward trend in their production accuracy. Gains in accuracy were maintained 2 months posttreatment for 2 of the 3 participants.

Conclusions

The current study provides preliminary evidence to support the use of explicit approaches to teach grammatical forms to children with ASD symptomology and motivates further investigation in this area.
The first steps of interstellar phosphorus chemistry
Authors: Chantzos J. , Rivilla V. M. , Vasyunin A. , Redaelli E. , Bizzocchi L. , Fontani F. , Caselli P.
Published: November 2019

Context. Phosphorus-bearing species are essential to the formation of life on Earth, however they have barely been detected in the interstellar medium. In particular, towards star-forming regions only PN and PO have been identified so far. Since only a small number of detections of P-bearing molecules are available, their chemical formation pathways are not easy to constrain and are thus highly debatable. An important factor still missing in the chemical models is the initial elemental abundance of phosphorus, that is, the depletion level of P at the start of chemical models of dense clouds.

Aims. In order to overcome this problem, we study P-bearing species in diffuse and translucent clouds. In these objects phosphorus is expected to be mainly in the gas phase and therefore the elemental initial abundance needed in our chemical simulations corresponds to the cosmic one and is well constrained.

Methods. For the study of P-bearing chemistry we used an advanced chemical model. We updated and significantly extended the P-chemistry network based on chemical databases and previous literature. We performed single-pointing observations with the IRAM 30 m telescope in the 3 mm range towards the line of sight to the strong continuum source B0355+508 aiming for the (2–1) transitions of PN, PO, HCP, and CP. This line of sight incorporates five diffuse and/or translucent clouds.

Results. The (2–1) transitions of the PN, PO, HCP, and CP were not detected. We report high signal-to-noise-ratio detections of the (1–0) lines of 13CO, HNC, and CN along with a first detection of C34S towards this line of sight. We have attempted to reproduce the observations of HNC, CN, CS, and CO in every cloud with our model by applying typical physical conditions for diffuse or translucent clouds. We find that towards the densest clouds with vLSR = −10, − 17 km s−1 the best-fit model is given by the parameters (n(H), AV, Tgas) = (300 cm−3, 3 mag, 40 K).

Conclusions. According to our best-fit model, the most abundant P-bearing species are HCP and CP (~10−10). The molecules PN, PO, and PH3 also show relatively high predicted abundances of ~10−11. We show that the abundances of these species are sensitive to visual extinction, cosmic-ray ionization rate, and the diffusion-to-desorption energy ratio on dust grains. The production of P-bearing species is favored towards translucent rather than diffuse clouds, where the environment provides a stronger shielding from the interstellar radiation. Based on our improved model, we show that the (1–0) transitions of HCP, CP, PN, and PO are expected to be detectable with estimated intensities of up to ~200 mK.
Von Hass-Sprache zur Kriminalität
Authors: Spitzer Manfred
Published: November 2019

Soziale Online-Medien verbreiten Sprache und damit auch Hass-Sprache. Sie wirken damit verstärkend auf die Auswirkungen von Hass-Sprache und befeuern Hass-Kriminalität, wie anhand zweier Studien zu den Auswirkungen von Facebook in Deutschland und von Twitter in Großbritannien gezeigt wird. Hass-Sprache als Ausdruck der freien Rede (wie in den USA) zu schützen, erscheint im Hinblick auf diese empirischen Erkenntnisse weniger geboten als behutsame Zensur, begleitet von Vernunft und dem beherzten Eintreten für Freiheit. Durch die heute mögliche Erfassung von Hass-Sprache in Echtzeit wird eine neue Form der prädiktiven Polizeiarbeit möglich, deren Vor- und Nachteile sorgfältig abzuwägen sind.
Markers of Metabolic Syndrome in Patients with Pituitary Adenoma: A Case Series of 303 Patients
Authors: Altuntaş Seher Çetinkaya , Evran Mehtap , Sert Murat , Tetiker Tamer
Published: November 2019

To assess the demographic characteristics and hormonal status of patients who presented to our clinic with pituitary adenoma and to demonstrate the presence, prevalence, and relationship of metabolic syndrome parameters in these patients. The study included 303 patients with known or newly diagnosed pituitary adenoma and 52 age- and sex-matched healthy controls. The patients were classified into 3 groups; acromegaly (ACRO) (n=54),prolactinoma (PRLoma) (n=163), and non-functional adenoma (NFA) (n=86). in 55.6% (n=172) and 52% (n=163) of the patients, respectively. The waist circumference of all patients (p<0.001) and body mass index (BMI) of patients with PRLoma (p=0.03) and ACRO (p<0.001) were found to be significantly higher than in the controls. The HbA1c, insulin and HOMA-IR values were significantly higher in the ACRO and PRLoma groups, whereas the insulin and HOMA-IR values were significantly higher in the NFA group compared with the control group (p<0.001 and p<0.001, respectively). When the 3 patient groups were compared, waist circumference and BMI were significantly higher in the ACRO group than in the PRLoma group (p=0.04 and p=0.03, respectively). In patients developing pituitary failure after treatment, age, waist circumference, plasma glucose, low-density lipoproteins and triglyceride values were significantly increased when compared with those without pituitary failure after treatment (p<0.001). In our study, it was found that there was increased metabolic and cardiovascular risk in functional pituitary adenoma and NFA.
Photochemical Deracemization of Chiral Sulfoxides Catalyzed by a Hydrogen-Bonding Xanthone Sensitizer
Authors: Wimberger Laura , Kratz Thilo , Bach Thorsten
Published: November 2019

Several chiral sulfoxides with a lactam hydrogen-bonding site were prepared and their photochemical behavior was studied in the presence of xanthone and thioxanthone sensitizers. While acyclic sulfoxides showed only decomposition, chiral benzothiazinone-1-oxides with a stereogenic sulfur atom underwent a stereomutation upon irradiation at λ = 366 nm in the presence of catalytic quantities of a xanthone sensitizer. A chiral xanthone with a 1,5,7-trimethyl-3-azabicyclo-[3.3.1]nonan-2-one backbone was employed in catalytic quantities (5 mol%) to achieve a deracemization reaction of racemic benzothiazinone-1-oxides in acetonitrile solution. Five substrates could be successfully deracemized in good yields and with up to 55% ee.
Base-Controlled One-Pot Chemoselective Suzuki–Miyaura Reactions for the Synthesis of Unsymmetrical Terphenyls
Authors: Li Xinmin , Feng Fangfang , Ren Changyue , Teng Yong , Hu Qinghong , Yuan Zeli
Published: November 2019

We report a chemoselective Suzuki–Miyaura reaction protocol of using bromophenyl fluorosulfonate as building block for the preparation of unsymmetrical terphenyls. The chemoselective cross-coupling of bromophenyl fluorosulfonate and arylboronic acids can be achieved by controlling base species without using any ligands. Under this methodology, various of m- and p-unsymmetrical terphenyls were obtained in moderate to good yields.
Copper-Catalyzed Aerobic Oxidative Alkynylation of 3,4-Dihydroquinoxalin-2-ones
Authors: Rostoll-Berenguer Jaume , Blay Gonzalo , Pedro José R. , Vila Carlos
Published: November 2019

Herein, we described a ligand-free copper-catalyzed aerobic oxidative functionalization of 3,4-dihydroquinoxalin-2(1H)-ones with terminal alkynes using visible-light and oxygen as terminal oxidant to give 3-ethynyl-3,4-dihydroquinoxalin-2(1H)-one, cyclic propargylic amines, in moderate to good yields. Moreover, we demonstrate the versatility of the 3-ethynyl-3,4-dihydroquinoxalin-2(1H)-ones obtained by preparing several 3,4-dihydroquinoxalin-2-one derivatives.
The Difference in Thyroid Stimulating Hormone Levels between Differentiated Carcinoma and Benign Enlargement
Authors: Rianto Bambang Udji Djoko , Wibowo Anton Sony , Herdini Camelia
Published: November 2019

Introduction Papillary and follicular thyroid carcinoma are common head and neck cancers. This cancer expresses a thyroid stimulating hormone (TSH) receptor that plays a role as a cancer stimulant substance. This hormone has a diagnostic value in the management of thyroid carcinoma.

Objective The present study aimed to determine the difference in TSH levels between differentiated thyroid carcinoma and benign thyroid enlargement.

Methods The present research design was a case-control study. The subjects were patients with thyroid enlargement who underwent thyroidectomies at the Dr. Sardjito General Hospital, Yogyakarta, Indonesia. Thyroid stimulating hormone levels were measured before the thyroidectomies. The inclusion criteria for the case group were: 1) differentiated thyroid carcinoma, and 2) complete data; while the inclusion criteria for the control group were: 1) benign thyroid enlargement, and 2) complete data. The exclusion criteria for both groups were: 1) patients suffering from thyroid hormone disorders requiring therapy before thyroidectomy surgery, 2) patients receiving thyroid suppression therapy before the thyroidectomy was performed, and 3) patients suffering from severe chronic diseases such as renal insufficiency, and severe liver disease.

Results There were 40 post-thyroidectomy case group patients and 40 post-thyroidectomy control group patients. There were statistically significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement (p = 0.001; odds ratio [OR] = 8.42; 95% confidence interval [CI]: 3.19–36.50).

Conclusion Based on these results, it can be concluded that there were significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement.
Prevalence of Mild Hearing Loss in Schoolchildren and its Association with their School Performance
Authors: Elbeltagy Reem
Published: November 2019

Introduction Hearing is important for the proper development of every child, especially for those younger than 5 years of age, because it helps in the development of language and speech. Emotional and social problems, as well as issues with academic performance, can result from hearing loss even of mild degree. Early diagnosis and management can overcome those negative impacts.

Objective To determine the prevalence of mild hearing loss in primary-school children and its association with their school performance.

Methods A comparative cross-sectional study was conducted at a regular school. The study included the random selection of 120 apparently normal students (aged 6-9 years) who were considered as having normal hearing by their parents. A total of 20 students were excluded from the study due to the presence of wax in their ears. Finally, the study was conducted with 100 students. All participants were subjected to a basic audiological evaluation, and the Screening Instrument for Targeting Educational Risk (SIFTER) questionnaire was given to their teachers to evaluate their school performance.

Results From a total of 100 students, we confirmed that 23 (23%) had mild hearing loss, 17 (17%) had bilateral conductive hearing loss, and 6 (6%) had bilateral sensorineural hearing loss. The students who had low attention and communication performance were significantly associated with mild hearing loss.

Conclusion The prevalence of mild hearing loss was of 23% (23 cases). This problem had an effect on the communication and attention in school; and it might affect academic performance later in life. A hearing assessment is highly recommended for every child, especially those who have a low rate of academic performance.
Severe Dizziness Related to Postural Instability, Changes in Gait and Cognitive Skills in Patients with Chronic Peripheral Vestibulopathy
Authors: Coelho Almir Resende , Perobelli Júlia Licursi Lambertti , Sonobe Lilian Shizuka , Moraes Renato , Barros Camila Giacomo de Carneiro , Abreu Daniela Cristina Carvalho de
Published: November 2019

Introduction Peripheral vestibular disorders can lead to cognitive deficits and are more common in elderly patients.

Objective To evaluate and correlate cognitive, balance and gait aspects in elderly women with chronic peripheral vestibular dizziness, and to compare them with elderly women without vestibular disorders.

Methods Twenty-two women presenting peripheral vestibular dizziness episodes for at least six months participated in the study. The individuals were categorized by dizziness severity level: moderate (n = 11) or severe (n = 11). The control group (n = 11) included women showing no vestibulopathy, light-headedness or dizziness. Cognitive assessments and semi-static and dynamic balance assessments were performed with the Balance Master (Neurocom International, Inc., Clackamas, OR), while the Dizziness Handicap Inventory provided a score for the severity of the symptoms. The groups were submitted to statistics of inference and correlation between cognitive, balance and stability variables.

Results The group with severe dizziness showed higher sway speed of the center of pressure in the anteroposterior direction, smaller step length, and slower gait than the control group. Regarding the cognitive variables, the group with severe dizziness symptoms presented significant correlations with stability and gait variables.

Conclusion The relationship between cognitive aspects, balance and gait was stronger in women with severe dizziness than in those with no vestibulopathy.
Audiological Abnormalities in Vitiligo Patients: A Hospital-Based Cross-Sectional Study
Authors: Prabha Neel , Arora Ripudaman , Chhabra Namrata , Jati Monalisa , Nagarkar Nitin M.
Published: November 2019

Introduction There are some discrepancies in the literature about the influence of vitiligo on auditory functions. According to some authors, vitiligo influences hearing, whereas others question such influence. Therefore, we conducted a study to evaluate audiological functions in vitiligo patients.

Objectives To determine the effect of vitiligo on auditory functions.

Methods A hospital-based observational study was done from January 2017 to July 2017. Clinically diagnosed cases of vitiligo were enrolled for the study. A complete otological examination was conducted in all patients.

Results Fifty-two patients (male: female 28:24) were included in the study. Ten patients (19.2%) had sensorineural hearing loss (SNHL). Seven patients (13.5%) had bilateral and 3 (5.7%) had unilateral SNHL. High frequency loss was seen in 17 out of 20 ears (10 affected patients), 6 ears had both low and high-frequency hearing loss. Of 12 ears with speech frequency involvement, mild hearing loss was seen in 5 and moderate to severe in 1 ear. Most cases of SNHL were detected in the age group 41 to 60 years old (63.6%), which was statistically significant (p-value 0.00).

Conclusion The results of this study suggest that vitiligo patients require routine monitoring for auditory functions for early identification of SNHL. Older subjects with vitiligo might be at a higher risk for audiological abnormalities. These patients should also be informed regarding the associated risk with noise and ototoxic drug exposure.
Anatomical Variation in the Drainage Pattern of Frontal Sinus – A Cadaveric Study
Authors: Gnanavelraja C. , Nalinakumari S. D. , Rajajeyakumar M.
Published: November 2019

Background A proper and detailed knowledge about the frontal sinus drainage pathway is essential for the radiologist to interpret the computed tomography scan of the paranasal air sinuses to find out normal and variant in the anatomy of frontal sinus ostium, and also for the surgeons to do endonasal sinus surgery particularly in the frontal sinus area with enough confidence and to give good postoperative result. With this background, the present study was focused to study the variation in the drainage pattern of frontal sinus in relation to uncinate process in cadaveric specimens.

Materials and Methods The midsagittal section of head and neck portion of 40 cadaveric specimens with intact frontal sinus and frontal sinus drainage pattern were selected. By careful dissection, pattern of frontal sinus drainage was identified and pattern of drainage of frontal sinus in relation with uncinate process was studied.

Result Frontal sinus drainage pattern is anteromedial to uncinate process (Type 1) in 28 specimens (70%) and posterolateral to uncinate process (Type 2) in 12 specimens (30%).

Conclusion The results of our study show that the frontal sinus drainage pattern is more commonly present anteromedial to uncinate process compared with posterolateral position. This variation in the drainage pattern of frontal sinus should be kept in mind by the radiologist to give proper radiological interpretation and by the surgeons to avoid intraoperative complications and also to give good postoperative result.
Appropriateness of Antibiotic Treatment Review following Blood Culture Collection
Authors: Dhanda Jaspreet , Gray James , Bashir Amreen , Khan Sanna
Published: November 2019

Objective Inappropriate antibiotic treatment can significantly affect antimicrobial resistance, resulting in treatments becoming less effective in the future. Previous studies have not identified the possible de-escalation rate. The aim of this study was to assess the appropriateness of antibiotic treatment in patients who have a blood culture collected, in particular, calculating how many days of antibiotics can be de-escalated.

Methods A patient series, observational study was conducted that included all patient blood culture, regardless of whether they were positive or negative, over a period of 4 days. The study was repeated three times to attain a larger sample. The adequacy of antibiotic treatment was determined based on microbiology results, prescription drug administration, and patient notes/charts.

Results Of the 69 suitable cases, 36 (52.17%) received appropriate treatment and 33 (47.83%) received inappropriate treatment. Of the inappropriate cases, it was calculated that 83 days of de-escalation were possible. Fifteen (21%) of the cases could have de-escalated use of meropenem.

Conclusion The results highlight that there is opportunity to review and de-escalate patient's treatment, after taking a blood culture and practices such as rationalizing antibiotic choices and educating physicians on reviewing antibiotics is appropriate.
Repair of Longitudinal Meniscal Tears by Single or Double Vertical Loop Sutures: In vitro Biomechanical Study under Cyclic Loading
Authors: Kurnaz Recep , Aşçı Murat , Ergün Selim , Akgün Umut , Güneş Taner
Published: November 2019

One of the factors affecting the healing of a meniscus repair is the primary stability of the tear. The purpose of this study is to compare single and double vertical loop (SVL vs. DVL) meniscal suture configurations by measuring elongation under cyclic loading and failure properties under ultimate load. We hypothesized that DVL configuration would have superior biomechanical properties than SVL. Twenty-two intact lateral menisci were harvested from patients who required total knee arthroplasty. A 20-mm longitudinal full-thickness cut was made 3 mm from the peripheral rim to simulate a longitudinal tear. Two groups were formed and group randomization was done according to patient age and gender (SVL group: mean age 68.3 years [range, 58–78 years], five males, six females; DVL group: mean age 67.4 years [range, 59–77 years], six males, five females). Cyclic loading was performed between 5 and 30 N at a frequency of 1 Hz for 500 cycles. Then, the meniscus repair construct was loaded until failure. Statistical analysis was performed using the t-test and the Mann–Whitney's U-test. During the early phases of cyclic loading, three specimens from each group failed because of suture pull out and are excluded from the study. At the end of 500 cycles, there was significantly less displacement in the DVL group than the SVL group (6.13 ± 1.04 vs. 9.3 ± 2.59 mm) (p < 0.05). No significant difference was found between groups regarding ultimate load to failure measurements (p > 0.05). All specimens in SVL and five specimens in DVL groups failed in the form of suture pull out from the meniscus tissue. Longitudinal meniscal tears repaired with DVL configuration had less elongation value under cyclic loading compared with SVL configuration. Because of its superior biomechanical properties, it would be more secure to repair large and instable longitudinal meniscal tears by the DVL technique. This is a level II study.
Human stickiness as a counterforce to brain drain: Purpose-driven behaviour among Tanzanian medical doctors and implications for policy
Authors: Emmanuel Ndikumana David , Elo Maria , Piekkari Rebecca
Published: November 2019

We explain why a group of Tanzanian medical doctors decided to stay in their home country despite a massive brain drain and pressure to migrate. We argue that purpose-driven behaviour among medical doctors serves as a counterforce to brain drain, fostering human stickiness in a developing country context. A sense of purpose provides a novel lens to understand voluntary non-migration of highly-skilled professionals under extreme conditions. Furthermore, incoming expatriate doctors build local capacity by sharing skills and expertise with Tanzanian doctors. This affects the medical doctors’ motives to migrate, further reducing brain drain. These individual-level decisions not to migrate find their application in policy. We advocate policies that support purpose-driven behaviour and generate long-term commitment to a location, while advancing short-term mobility for knowledge sharing. The policy initiatives are targeted at actors in the sending and receiving countries as well as in international organisations, covering concerted multi-layered policies to support family and community embeddedness, to facilitate the incoming of expatriate doctors and foreign exchange, and to cultivate benefits of circular migration. We argue that migration behaviour is more individually grounded and socio-emotionally constructed than what dominant economic-based explanations suggest.
A blow-up criterion for classical solutions to the Prandtl equations
Authors: Sun Yimin
Published: November 2019

In this paper, we obtain a blow-up criterion for classical solutions to the two-dimensional Prandtl equations under a monotonicity assumption in weighted Sobolev spaces. Our proof is based on nonlinear energy estimates inspired by Masmoudi and Wong [Commun. Pure Appl. Math. 68, 1683–1741 (2015)] and maximum principles for parabolic equations.
Threshold photodissociation dynamics of NO2 studied by time-resolved cold target recoil ion momentum spectroscopy
Authors: Ding Xiaoyan , Forbes R. , Kübel M. , Lee Kevin F. , Spanner M. , Naumov A. Yu. , Villeneuve D. M. , Stolow A. , Corkum P. B. , Staudte A.
Published: November 2019

We study the near-threshold photodissociation dynamics of NO2 by a kinematically complete femtosecond pump-probe scheme using a cold target recoil ion momentum spectrometer. We excite NO2 to the optically bright Ã2B2 state with a 400 nm pulse and probe the ensuing dynamics via strong field single and double ionization with a 25 fs, 800 nm pulse. The pump spectrum spans the NO(X2Π) + O(3P) dissociation channel threshold, and therefore, following internal conversion, excited NO2 is energetically prepared both “above threshold” (dissociating) and “below threshold” (nondissociating). Experimentally, we can clearly discriminate a weak two-photon pump channel from the dominant single-photon data. In the single ionization channel, we observe NO+ fragments with nonzero momentum at 200 fs delay and an increasing yield of NO+ fragments with near-zero momentum at 3.0 ps delay. For double ionization events, we observe a time-varying Coulombic kinetic energy release between the NO+ and O+ fragments impulsively created from the evolving “hot” neutral ground state. Supported by classical trajectory calculations, we assign the decreasing Coulombic kinetic energy release at longer time delays to the increasing average NO–O distances in the ground electronic state during its large amplitude phase space evolution toward free products. The time-resolved kinetic energy release in the double ionization channel probes the large amplitude ground state evolution from a strongly coupled “inner region” to a loosely coupled “outer region” where one O atom is on average much further away from the NO. Both the time evolution of the kinetic energy release and the NO+ angular distributions support our assignments.
Nonlinear terahertz emission in the three-dimensional topological insulator Bi2Te3 by terahertz emission spectroscopy
Authors: Fang Zhaoji , Wang Hangtian , Wu Xiaojun , Shan Shengyu , Wang Chun , Zhao Haihui , Xia Chenyi , Nie Tianxiao , Miao Jungang , Zhang Chao , Zhao Weisheng , Wang Li
Published: November 2019

The ultrafast optoelectronic response in topological insulators (TIs) has been recognized as one of the keys for applications on quantum computing and high-speed devices, which thus has attracted great attention recently. In this work, we systematically investigate the ultrafast transient terahertz emission excited by femtosecond laser pulses in Bi2Te3 with terahertz emission spectroscopy serving as an ultrafast and contactless detector. The nonlinear terahertz emission surpasses the terahertz emission from the sum of the drift and diffusion current contributions even at oblique incidence with an incident angle up to 70°, manifesting remarkable surface nonlinear effects on TIs. Quantitatively comprehensive microscopic analysis of the nonlinear terahertz emission origins indicates the 120°-periodic azimuth-angle dependence, which reveals a microscopic picture that the nonlinear current flows along the Bi-Te bonds. Our exploration not only enhances the microscopic understanding of the nonlinear responses in TIs on a femtosecond timescale but also lays a foundation for their applications on high-speed and low-power-consumption devices and systems.
A setup for studies of laminar flame under microwave irradiation
Authors: Nilsson E. J. K. , Hurtig T. , Ehn A. , Fureby C.
Published: November 2019

Plasma assisted combustion is a very active research field due to the potential of using the technology to improve combustion efficiency and decrease pollutant emission by stabilizing lean burning flames. It has been shown in a number of studies that a small amount of electrical energy can be deposited in the flame by applying microwaves, resulting in enhanced flame propagation and thus improved flame stabilization and delayed lean blow-out. However, the effects have not yet been properly quantified since there are significant experimental challenges related to the determination of both the laminar burning velocity and the electric field strength. In the present work, a novel setup is described, where a well-defined burner system is coupled to a microwave cavity. The burner is of heat flux type, where a flat laminar flame is stabilized on a perforated burner head. The advantage of this burner for the current use is that the method and related uncertainties are well studied and quantified, and the geometry is suitable for coupling with the microwave cavity. The setup, experimental procedure, and data analysis are described in detail in this article. Laminar burning velocity for a methane-air flame at ϕ = 0.7 is determined to certify that the burner works properly in the microwave cavity. The flame is then exposed to pulsed microwaves at 1 kHz with a pulse duration of 50 µs. The laminar burning velocity at these conditions is determined to be 18.4 cm/s, which is an increase by about 12% compared to the laminar burning velocity that is measured without microwave exposure. The setup shows potential for further investigations of lean flames subjected to various microwave pulse sequences. The data are of high quality with well-defined uncertainties and are therefore suitable to use for validation of chemical kinetics models.
Orthogonal polynomials, asymptotics, and Heun equations
Authors: Chen Yang , Filipuk Galina , Zhan Longjun
Published: November 2019

The Painlevé equations arise from the study of Hankel determinants generated by moment matrices, whose weights are expressed as the product of “classical” weights multiplied by suitable “deformation factors,” usually dependent on a “time variable” t. From ladder operators [see A. Magnus, J. Comput. Appl. Math. 57(1-2), 215–237 (1995)], one finds second order linear ordinary differential equations for associated orthogonal polynomials with coefficients being rational functions. The Painlevé and related functions appear as the residues of these rational functions. We will be interested in the situation when n, the order of the Hankel matrix and also the degree of the polynomials Pn(x) orthogonal with respect to the deformed weights, gets large. We show that the second order linear differential equations satisfied by Pn(x) are particular cases of Heun equations when n is large. In some sense, monic orthogonal polynomials generated by deformed weights mentioned below are solutions of a variety of Heun equations. Heun equations are of considerable importance in mathematical physics, and in the special cases, they degenerate to the hypergeometric and confluent hypergeometric equations. In this paper, we look at three types of weights: the Jacobi type, the Laguerre type, and the weights deformed by the indicator function of χ(a,b)(x) and the step function θ(x). In particular, we consider the following Jacobi type weights: (1.1) xα(1 − x)βe−tx, x ∈ [0, 1], α, β, t > 0; (1.2) xα(1 − x)βe−t/x, x ∈ (0, 1], α, β, t > 0; (1.3)  (1−x2)α(1−k2x2)β, x∈[−1,1], α,β>0, k2∈(0,1); the Laguerre type weights: (2.1) xα(x + t)λe−x, x ∈ [0, ∞), t, α, λ > 0; (2.2) xαe−x−t/x, x ∈ (0, ∞), α, t > 0; and another type of deformation when the classical weights are multiplied by χ(a,b)(x) or θ(x): (3.1)  e−x2(1−χ(−a,a)(x)), x∈R, a>0; (3.2)  (1−x2)α(1−χ(−a,a)(x)), x∈[−1,1], a∈(0,1), α>0; (3.3) xαe−x(A + Bθ(x − t)), x ∈ [0, ∞), α, t > 0, A ≥ 0, A + B ≥ 0. The weights mentioned above were studied in a series of papers related to the deformation of “classical” weights.
Measurements error propagation and its sensitivity analysis in the aero-engine multistage rotor assembling process
Authors: Zhang Maowei , Liu Yongmeng , Sun Chuanzhi , Wang Xiaoming , Tan Jiubin
Published: November 2019

The purpose of this paper is to research the measurements error propagation principle about the measurement-assembly equipment of aero engine multistage rotor, besides analyze the effect of guide linear motion and turntable rotational motion on the final alignment error. Furthermore, we can improve the measurement and assembly accuracy of the aero engine multistage rotor. In this paper, a novel error analysis method related to measurement-assembly equipment was proposed. First, the topology of the measuring equipment was established based on the multibody system theory, the error propagation path was constructed by using the low order body sorting method. Second, the error transfer model of the linear motion and the rotational motion were established by using the homogeneous coordinate transformation matrix, and the total measurement terminal errors introduced by the equipment were calculated. Finally, through numerical simulation, the magnitude of the measurement terminal offset error was obtained, sensitivity analysis was performed to calculate key error sources. Measurement accuracy not only depended on the accuracy of the sensor but also closely related to the accuracy of the measurement-assembly equipment. Through the simulation verification, when the linearity error is 0.1 μm and the angular error is 0.1″, the final cumulative offset displacement error is about −0.1002 μm to −0.0998 μm with a probability of 97%. Different type errors have different effects on the results. We can give a conclusion that linear guide alignment error and verticality error are the primary error sources, and the angle error of the turntable need to be improved.
Theory of ultrafast x-ray scattering by molecules in the gas phase
Authors: Simmermacher Mats , Moreno Carrascosa Andrés , E. Henriksen Niels , B. Møller Klaus , Kirrander Adam
Published: November 2019

We recast existing theory of ultrafast time-resolved x-ray scattering by molecules in the gas phase into a unified and coherent framework based on first-order time-dependent perturbation theory and quantum electrodynamics. The effect of the detection window is analyzed in detail and the contributions to the total scattering signal are discussed. This includes the coherent mixed component caused by interference between scattering amplitudes from different electronic states. A new, detailed, and fully converged simulation of ultrafast total x-ray scattering by excited H2 molecules illustrates the theory and demonstrates that the inelastic component can contribute strongly to the total difference scattering signal, i.e., on the same order of magnitude as the elastic component.
Three-dimensional simulations of turbulent mixing in spherical implosions
Authors: El Rafei M. , Flaig M. , Youngs D. L. , Thornber B.
Published: November 2019

High-resolution large-eddy simulations of turbulent mixing at the inner surface of a dense shell which undergoes forced compression by a spherically imploding shock wave are presented. Perturbations on the inner surface grow as a result of Richtmyer-Meshkov and Rayleigh-Taylor instabilities and effects related to geometric convergence and compressibility. Three different cases with different initial surface perturbations, one broadband and two narrowband, are considered. The perturbation power spectrum is related to the mode number via Pℓ ∝ ℓn, where the case with broadband perturbations has n = −2, and modes in the range ℓ = 6–200. The narrowband perturbations have n = 0 and modes in the range ℓ = 50–100 and ℓ = 100–200. The simulations are carried out in spherical coordinates using the PLUTO hydrodynamics code. Results on the mix layer width, molecular mix, and turbulent kinetic energy distribution are presented, demonstrating clearly the impact of the amplitude and spectral form of the initial perturbation on the evolution of integral properties. A recently developed model predicting the growth of single mode perturbations in spherical implosions including shock waves is extended to predict mix layer amplitudes for broadband and narrowband cases, along with a model proposed by Mikaelian [“Rayleigh-Taylor and Richtmyer-Meshkov instabilities and mixing in stratified spherical shells,” Phys. Rev. A 42, 3400–3420 (1990)]. The resultant layer amplitude predictions from the new model are in good agreement with the numerical results while the longest wavelengths are not yet saturated, while Mikaelian’s model agrees well where the initial modes are saturated.
The effect of the voltage waveform on performance of dielectric barrier discharge plasma actuator
Authors: Nakano Asa , Nishida Hiroyuki
Published: November 2019

Improving the performance of a dielectric barrier discharge plasma actuator (DBDPA) is required to further its practical use. In this study, the effects on DBDPA performance by the AC voltage waveform are experimentally investigated. For this purpose, we performed thrust measurements, consumption power measurements, and body force analysis using particle-image-velocimetry. Observations obtained using the basic symmetric waveforms yielded that changing the voltage gradient (dV/dt) like a sinusoidal waveform is effective to produce a strong body force with low consumption power. Therefore, we firstly propose the waveforms systematically composed of combinations of steep and gradual voltage slopes. In the investigation about proposed waveforms, we found that the negative steep-gradual voltage profile is effective for strong thrust induction, that is, the steep slope results in strong body force generation by a strong discharge, and the gradual slope maintains that body force. On the other hand, the effective positive-going voltage profile is different depending on the negative voltage profile. The positive steep-gradual profile works to induce body force with the same mechanism as the negative one, while the gradual-steep profile maintains the body force generated in the last negative-going voltage period and enhances the body force generated in the forthcoming negative-going voltage period. However, a positive-going voltage period itself generates only a weak body force independent from the voltage profiles. From the investigation, we found that a combination of the steep-gradual profile in both the negative- and positive-going voltage periods provides the strongest thrust generation. In addition, we further optimized the voltage waveform by changing the proportion of the negative-going voltage period in one AC cycle. We found that a waveform with a 70% negative-going voltage period achieves more than 40% stronger thrust and 20% higher efficiency than those of the sinusoidal waveform. Also, the waveform with an 80% negative-going voltage period yields over 35% stronger thrust with the highest efficiency, 25% higher than the sinusoidal waveform.
Electro-thermal excitation of parametric resonances in double-clamped micro beams
Authors: Torteman B. , Kessler Y. , Liberzon A. , Krylov S.
Published: November 2019

We report on a simple yet efficient approach allowing direct electrothermal excitation of parametric resonance (PR) in double-clamped flexible nano- and microscale beams. The application of a time-harmonic voltage between the beam's ends leads to the electric current and Joule's heating of the entire beam, which induces a time-periodic axial stress and results in excitation of the structure lateral vibrations through the PR mechanism. The proposed approach has an advantage, simplifying fabrication and integration and reducing the influence of residual stress, and thermal mismatch, unlike conventional piezoelectric, photothermal, or electrostatic actuation approaches, which require additional piezoelectric layers, light sources, or electrodes in the proximity of a vibrating beam. Single crystal silicon, nominally 500 μm long, 30 μm wide, and 5 μm thick beams were fabricated by deep reactive ion etching and operated at a pressure of ≈1.9 mTorr. The experimental results, consistent with the reduced order and numerical model predictions, demonstrate the feasibility of the suggested excitation scenario, which could be implemented in resonant sensors, timing devices, signal processing, and micro and nanomechanical logical elements.
A coarse-grained deep neural network model for liquid water
Authors: Patra Tarak K , Loeffler Troy D. , Chan Henry , Cherukara Mathew J. , Narayanan Badri , Sankaranarayanan Subramanian K. R. S.
Published: November 2019

We introduce a coarse-grained deep neural network (CG-DNN) model for liquid water that utilizes 50 rotational and translational invariant coordinates and is trained exclusively against energies of ∼30 000 bulk water configurations. Our CG-DNN potential accurately predicts both the energies and the molecular forces of water, within 0.9 meV/molecule and 54 meV/Å of a reference (coarse-grained bond-order potential) model. The CG-DNN water model also provides good prediction of several structural, thermodynamic, and temperature dependent properties of liquid water, with values close to those obtained from the reference model. More importantly, CG-DNN captures the well-known density anomaly of liquid water observed in experiments. Our work lays the groundwork for a scheme where existing empirical water models can be utilized to develop a fully flexible neural network framework that can subsequently be trained against sparse data from high-fidelity albeit expensive beyond-DFT calculations.
Optimization of Pb content in enhancing ferroelectricity and shifting the Tc of BaTiO3 to a higher temperature
Authors: Amin Ruhul , Khatun Nasima , Sen Somaditya
Published: November 2019

Sol-gel prepared homogeneous Ba1 − xPbxTiO3 ceramics reveal elongation along the c-axis and contraction along the a-axis, thereby increasing the tetragonality (c/a ratio) with Pb doping. Raman spectral shape changes with composition and hardening and softening of vibrational modes are discussed and correlated to the structure and oxygen content. A new differential mode (in BaTiO3) predicted theoretically between two A1 Raman modes is experimentally detected at ∼71 cm−1. Tetragonal to cubic phase transition temperature (Tc) increases linearly with an increase in Pb content. Hence, appropriate Pb addition enhances Tc and thereby retains ferroelectricity until it reaches a higher temperature in the ceramics. Ferroelectricity in the solid solution was confirmed to enhance with an increase in Pb content from field-dependent polarization measurements. With Pb content, more than 50%, ferroelectric properties of the ceramics degrade and the materials become lossy due to the presence of O-defects originating from Pb-loss. This work provides an insight into how two well-known ferroelectric properties can be mixed to enhance its properties.
Atomic origin of Ti-deficient dislocation in SrTiO3 bicrystals and their electronic structures
Authors: Li Xujing , Chen Shulin , Li Mingqiang , Liu Kaihui , Bai Xuedong , Gao Peng
Published: November 2019

Dislocations in perovskite oxides have important impacts on their physical and chemical properties, which are determined by their unique atomic environments. In the present study, the structure of dislocations in a 10° low-angle grain boundary of SrTiO3 that was fabricated in an N2 annealing atmosphere is characterized by spherical aberration-corrected scanning transmission electron microscopy and spectroscopy. We find that the dislocation cores are deficient in titanium (Ti) due to Sr substitution and under Ti occupancy. This differs from previously reported dislocation cores fabricated in an air annealing atmosphere, which show Ti enrichment. The presence of oxygen vacancies and partially reduced Ti are also detected in these Ti-deficient dislocation cores. These findings indicate that atomic structures of dislocations can be very different even when they have the same Burgers vectors. Controllable element segregation in the dislocations and grain boundaries via bicrystal engineering should be very useful for designing devices with novel functions.
Improving electronic properties and mechanical stability of Yb14MnSb11 via W compositing
Authors: Cerretti G. , Villalpando O. , Fleurial J.-P. , Bux S. K.
Published: November 2019

Many of the missions proposed and successfully completed by the National Aeronautics and Space Administration seek to scientifically investigate remote locations in our solar system, in particular to better understand the origin, evolution and structure of planetary systems. Long-lived, robust power systems are a fundamental capability for such missions, and radioisotope thermoelectric generators (RTGs) have proven to be a reliable power for exploration missions in deep space for the past 50 years. With increasing power needs for future missions, the improvement of thermoelectric materials’ conversion efficiency is necessary. In this paper, we show how compositing with inert metallic inclusions can be efficiently used to improve the electronic properties of Yb14MnSb11. In this study, we found that the power factor of the p-type high temperature material, Yb14MnSb11, increases from ∼8 to ∼11.5 μW cm−1 K−2 when composited with 5 vol. % W particles. At the same time, the composite samples have a higher thermal conductivity and, therefore, the final zT remains unchanged (∼1.3 at 1273 K). Preliminary hardness tests indicated a qualitative increase in mechanical robustness for the tungsten composite samples. These results can play a relevant role in device design and performance, improving the thermoelectric impedance matching for leg segmentation and helping overcome the intrinsic brittleness of high temperature ceramics such as Yb14MnSb11 for advanced device fabrication.
Design of a compact four degree-of-freedom active compensation system to restrain laser’s angular drift and parallel drift
Authors: Liu Shujie , Tan Siyuan , Huang Yubin , Wang Yayong , Fan Kuang-Chao
Published: November 2019

The laser collimation technique is widely used in science research and industrial applications. The pointing stability will be affected by the common problem of beam drift. A compact active compensation system is presented in this paper. The angular drift of the diode laser and parallel shift caused by angular drift compensation can be measured and actively compensated through a 4 degree-of-freedom active compensation module. The design of the whole system is compact, which makes it easy to be integrated into a measurement system. Experimental results indicate that the approach proposed can enhance the point stability to 88% for only angular drift compensation and further to 96.1% if both angular drift and parallel shift are compensated. This compensation module for point stability control can be used in any laser applications.
Edge computing in space: Field programmable gate array-based solutions for spectral and probabilistic analysis of time series
Authors: Opincariu Laurenţiu , Deak Norbert , Creţ Octavian , Echim Marius , Munteanu Costel , Văcariu Lucia
Published: November 2019

This paper addresses the problem of performing time series analysis on-board a spacecraft, where the number of constraints is much bigger than for applications running in regular (i.e., ground-based) environments. An objective of modern spacecraft technologies designed for space exploration is to perform on-board data processing tasks, in order to increase the amount of data available for scientific analysis. Field Programmable Gate Array (FPGA) devices are considered as good candidates for hardware implementations of such systems. In order to optimize the usage of on-board resources, FPGAs share their resources between several digital signal processing (DSP) algorithms. In this paper, we describe the design and implementation of such an optimized design where two DSP algorithms are implemented on the same FPGA: (1) the power spectral density and (2) the multiscale probability distribution functions. The entire implementation process is described in detail, including a discussion about the main architectural choices. The proposed solutions focus on optimization of area, speed, and power. The tests performed, on both synthetic and real data, demonstrate the feasibility of our approach and constitute the first step toward porting the design on space-grade FPGAs.