bluuebunny/crossref_metadata_2025 huggingface dataset:
An N-of-1 Randomized Controlled Trial of Interventions for Children With Inconsistent Speech Sound Errors
Authors: Rvachew Susan , Matthews Tanya
Published: September 2019

Purpose

The aim of this study was to test the hypothesis that children with inconsistent speech errors would respond differentially to 1 of 3 specific interventions depending on their primary underlying impairment: Children with deficient motor planning were expected to respond best to an auditory–motor integration (AMI) intervention, and children with deficient phonological planning were expected to respond best to a phonological memory and planning (PMP) intervention.

Method

Twelve participants were diagnosed with a motor planning (
n
= 7) or phonological planning (
n
= 5) deficit based on a comprehensive assessment, which included the Syllable Repetition Task as an important source of diagnostic evidence. An N-of-1 randomized controlled trial was used. Each child experienced all 3 interventions: AMI, PMP, and control (CTL); however, these interventions were randomly allocated to sessions within weeks (3 sessions per week × 6 weeks for 18 sessions). The AMI intervention procedures targeted knowledge of the acoustic–phonetic target and integration of auditory and somatosensory feedback during speech practice. The PMP intervention procedures targeted segmenting and recompiling the phonological plan for each word. The CTL intervention was standard drill practice. The child was taught 5 pseudowords in a meaningful context in each intervention condition.

Results

Same-day (SD) probes assessed transfer from taught pseudowords to untaught real words, and next-day (ND) probes assessed retention of that learning. Nonparametric resampling tests with pooling of
p
values across children with the same diagnosis were used to assess the results. Pooled
p
values indicated a significant benefit of AMI over PMP for the group with a motor planning deficit (
p
= 2.01E-04 for SD probes and 2.97E-03 for ND probes) and a significant benefit of PMP over AMI for the group with a phonological planning deficit (
p
= 1.22E-02 for SD probes and 1.32E-02 for ND probes). Response to the CTL intervention was variable within groups.

Conclusion

In this study, the child's underlying psycholinguistic deficit helped to predict response to intervention.
Motor Performance in Children With Childhood Apraxia of Speech and Speech Sound Disorders
Authors: Iuzzini-Seigel Jenya
Published: September 2019

Purpose

This study sought to determine if (a) children with childhood apraxia of speech (CAS), other speech sound disorders (SSDs), and typical development (TD) would perform differently on a standardized motor assessment and (b) whether comorbid language impairment would impact group differences.

Method

Speech, language, and motor abilities were assessed in children with CAS (
n
= 10), SSD (
n
= 16), and TD (
n
= 14) between the ages of 43 and 105 months. Motor skills were evaluated using the Movement Assessment Battery for Children–Second Edition (
Henderson, Sugden, & Barnett, 2007
), a behavioral assessment that is sensitive in identifying fine/gross motor impairments in children with a range of motor and learning abilities. Data were reanalyzed after reclassifying children by language ability.

Results

The CAS group performed below the normal limit on all components of the motor assessment and more poorly than the TD and SSD groups on Aiming and Catching and Balance. When children were reclassified by language ability, the comorbid CAS + language impairment group performed worse than the SSD-only and TD groups on Manual Dexterity and Balance and worse than the TD group on Aiming and Catching; all 7 children with CAS + language impairment evidenced performance in the disordered range compared to 1 of 3 children in the CAS-only group and 2 of 6 children in the SSD + language impairment group.

Conclusions

Children with CAS + language impairment appear to be at an increased risk for motor impairments, which may negatively impact social, academic, and vocational outcomes; referrals for motor screenings/assessments should be considered. Findings may suggest a higher order deficit that mediates cognitive–linguistic and motor impairments in this population.
New explicitly invertible approximation of the function involved in LDPC codes density evolution analysis using a Gaussian approximation
Authors: Vatta F. , Soranzo A. , Comisso M. , Buttazzoni G. , Babich F.
Published: September 2019

Low density parity check (LDPC) codes are still intensively studied investigating their iterative decoding convergence performance. Since the probability distribution function of the decoder's log‐likelihood ratio messages was observed to be approximately Gaussian, a variety of low‐complexity approaches to this investigation were proposed. One of them was presented in Chung et al.'s 2001 paper, involving the function , therein specified, and its inverse. In this Letter, a new approximation of the function is given, such that, unlike the other approximations found in the literature, it is defined by a single expression (i.e. it is not piecewise defined), it is explicitly invertible, and it has less relative error in any x than the other approximations.
Moving target detection on an iron‐bridge using phase analysis for automotive FMCW radar
Authors: Kim Daehyun , Lee Jingu , Jeong Seonghee , Kim Younglok
Published: September 2019

When driving on an iron‐bridge, stationary iron‐clutters cause disturbances in the detection of a moving target in an automotive radar system. In this Letter, the authors propose a moving target detection method that utilises phase similarity of the spatial domain on an iron‐bridge. To analyse the spatial domain via the array antenna signal of the up‐ and down‐chirp beat‐frequencies, the frequency‐modulated continuous wave (FMCW)‐phased array radar signal was used. It is possible to match the up‐ and down‐chirp beat‐frequencies of each object, moving target, and stationary iron‐clutters, by using the proposed method. Not only the moving target but also the ego‐vehicle and moving target velocity are detected through this matching. The suitability of the proposed method is verified by on‐road measurement data using a 77 GHz FMCW‐phased array radar.
Array diagnosis using signal subspace clustering in MIMO radar
Authors: Zhang Tingxiao , Chen Jinli , Chen Xuan
Published: September 2019

In multiple‐input multiple‐output (MIMO) radar system, timely array diagnosis method is needed for transmit and receive arrays. To avoid using extra probes or measurements, a novel signal subspace clustering‐based array diagnosis method is proposed. By exploiting the relationship between the signal subspace extracted from the covariance matrix and the steering matrix in MIMO radar, the feature of the anomalous data points in signal subspace caused by faulty elements is examined. Consequently, the anomalies are grouped into one cluster by density peaks clustering algorithm, and the faulty antennas in transmit and receive arrays can be identified based on the clustering results. Numerical simulation results demonstrate the superiority of the proposed approach in array diagnosis problem for MIMO radar.
Interval estimation of actuator fault by interval analysis
Authors: Zhang Wenhan , Wang Zhenhua , Shen Yi , Guo Shenghui , Zhu Fanglai
Published: September 2019

This study proposes an interval estimation method of actuator fault for linear discrete‐time system. An augmented descriptor system, which is equivalent to the original system, is formulated by letting the actuator fault term be an auxiliary state. Then, an fault estimation observer is constructed to attenuate the effect of unknown but bounded disturbances and measurement noise. By using interval analysis technique, the interval estimation of actuator fault can be obtained. Finally, a DC servo‐motor example is given to show the effectiveness and superiority of the proposed method.
3D‐printed 4‐zone Ka‐band Fresnel lens: design, fabrication, and measurement
Authors: Jeong Kyoung Ho , Ghalichechian Nima
Published: September 2019

A planar and thin‐grooved Fresnel lens is a great candidate for gain enhancement in millimetre wave communication, imaging systems, and wireless power transfer applications. The authors report the design, fabrication, and measurement of a 3D‐printed Fresnel lens, using a single material. A low‐profile (1.2 λ thick) 4‐zone Fresnel lens with 16 annular rings is designed with a focal length of 40 mm (≃4λ) operating at 30 GHz. Authors’ design consists of four‐step heights with outer radius of 69 mm (6.9λ). Permittivity and loss tangent of polylactic acid are measured to be 2.79 and 0.0048 at 30 GHz, respectively. Focusing ability of the lens is studied using full‐wave simulation. The lens is fabricated using a table‐top commercial fused deposition modelling printer. The surface roughness, step heights, and radii of each zone are measured and verified using a 3D optical profilometer. Impact of the 3D‐printed limitation on performance of the device is discussed. The gain of the fabricated prototype is measured, in conjunction with a horn antenna, in an anechoic chamber. Pattern measurement results illustrate 6.6 dB gain enhancement at broadside at 30 GHz. Gain enhancing behaviour is studied at three different focal lengths and frequencies of 29–31 GHz.
Dual‐objective control strategy for maximum power and efficiency point tracking in wirelessly powered biomedical implanted devices
Authors: Nasr Fatemeh , Madani Seyed M. , Niroomand Mehdi
Published: September 2019

Wireless charging is widely considered as a safe and reliable way for powering biomedical implants, as it avoids problems like surgical infection. Wireless power transfer (WPT) systems are desired to work efficiently against variations in coil–coil distance or output load. On the other hand, to maintain the maximum overall efficiency of the WPT system, the high frequency (HF) power amplifier, used to feed WPT system, must operate at optimal zero‐voltage switching (ZVS) condition. In this paper, an automated dual‐objective control strategy adaptive to variations in coil–coil distance or output load is proposed which ensures both targets of tracking maximum power point and operating at optimal ZVS condition by adjusting operating frequency and duty‐cycle of switching voltage of HF power amplifier, respectively; that is while there have been few studies which have addressed both the two targets. To evaluate the effectiveness of the proposed strategy, a PCB prototype, operating at 800 kHz, is fabricated. Experimental results, demonstrating the proposed strategy increases transferred power from 23 mW to about 45 mW, are in good agreement with theoretical predictions. Additionally, while implanting the receiver coil in a real biological tissue, experiments show only 2% of degradation in power transfer efficiency as well as no frequency shift.
Compact ultra‐wideband antenna: improvement of gain and FBR across the entire bandwidth using FSS
Authors: Mondal Rahul , Reddy P. Soni , Sarkar Debasree Chanda , Sarkar Partha Pratim
Published: September 2019

In this paper, a highly compact ultra‐wideband (UWB) monopole antenna with high gain is proposed. The UWB monopole antenna consists of U‐shaped radiating patch. The ground plane comprises of edge‐truncated partial rectangular metallic plane with a rectangular slot at the centre of the top edge. The proposed antenna having a very compact dimension of 16 mm × 22 mm × 1.6 mm is compatible and highly suitable for compact wireless systems. Further for enhancement of directivity of the UWB antenna, a patch type frequency selective surface (FSS) is placed below the antenna. The combined FSS‐antenna structure operates with high gain (peak gain of 9.4 dBi) across the entire UWB range (3.1–18.6 GHz). The proposed design also offers an appreciably high front‐to‐back lobe ratio of ∼10 dB across the entire UWB range. The simulated results are verified experimentally and the results are discussed in detail. The overall dimension of the proposed FSS integrated composite antenna is 52 mm × 62.5 mm × 23.2 mm, which is highly relevant for high‐gain applications.
Eight‐element‐based MIMO antenna with CP behaviour for modern wireless communication
Authors: Biswal Sonika Priyadarsini , Das Sushrut
Published: September 2019

In this work, an eight‐element multiple‐input multiple‐output (MIMO) antenna with circular polarisation (CP) ability is proposed. The proposed antenna consists of eight off‐centred fed modified rectangular open‐loop resonating radiators. CP behaviour is realised by utilising a narrow slit on the loop and a modified ground plane. Measurement reveals that the proposed CP‐MIMO antenna occupies an overlapping 10 dB return loss bandwidth and a 3 dB axial ratio bandwidth over the frequency span of 5–6 GHz with inter‐element isolation > 8 dB. Essential diversity and multiplexing performances are estimated intuitively by means of the envelope correlation coefficient and ergodic channel capacity, which lie within their adequate range. To ensure its applicability in user terminal devices and confirm the use of other electronic circuitry, the antenna performances are also investigated in the presence of a conducting sheet which is commonly grounded with the antenna ground plane.
Parameter retrieval of aircraft wake vortex based on its max–min distribution of Doppler velocities measured by a Lidar
Authors: Gao Hang , Li Jianbing , Chan P.W. , Hon K.K.
Published: September 2019

Aircraft wake vortex is a sort of turbulence generated by a flying aircraft. It has attracted much attention in aviation safety area because it may cause a following aircraft to roll out of control. This study proposes a simple method to retrieve the characteristic parameters of an aircraft wake based on the max–min distribution of Doppler velocity over a RHI (range‐height indicator). First, the vortex cores are determined by the Doppler velocity's cross‐over structure. Second, the circulations are obtained by the velocity differences between the points above the vortex core and the corresponding below ones. During this process, the impact of background wind can be well mitigated. Basically, the new method is with a low computation cost and an acceptable accuracy. Its good performance has been verified by simulations and field detection data recorded in Hong Kong International Airport.
Through‐the‐wall imaging using Wi‐Fi signals
Authors: Zhong Wei , He Kai , Li Lianlin
Published: September 2019

In this work, the authors experimentally investigate the high‐resolution three‐dimensional through‐the‐wall imaging exploiting commodity Wi‐Fi signals in an indoor environment. The authors also provide physical insights into this novel imaging strategy, which has been derived from the Huygens' principle. In the authors’ experiments, a pair of antennas are used to acquire the Wi‐Fi signals reflected from the scene in a synthetic aperture mode. The classical filtered back propagation (FBP) algorithm is then used to form the image based on these signals. The authors use an IEEE 802.11n protocol wireless router working at 2.4 GHz with bandwidth of 20 MHz. It can be faithfully expected that such imaging technique can open an exciting new door for various practical applications including safety screening and others.
Improved SSD‐based transmission tower detection in SAR images
Authors: Gao Yuan , Yang Wei , Li Chunsheng , Zou Fei
Published: September 2019

SAR transmission tower detection is essential to transmission system monitoring and maintenance. Various methods have been proposed to detect transmission tower by using shallow feature. With the development of the deep learning based on convolutional neural network, this study proposed an improved SSD‐based transmission tower detection method by introducing deep learning‐based technique. First, SSD, a state‐of‐the‐art object detection method, is analysed in detail. Then, the algorithm is modified to fit authors’ specific domain. According to the experiment results in real SAR images, it is showed that the modified method gains better detection performance. Finally, ablation experiments are also performed to confirm each modification step produces better result.
The VANDELS survey: the role of ISM and galaxy physical properties in the escape of Lyα emission in z ∼ 3.5 star-forming galaxies
Authors: Marchi F. , Pentericci L. , Guaita L. , Talia M. , Castellano M. , Hathi N. , Schaerer D. , Amorin R. , Bolzonella M. , Carnall A. C. , Charlot S. , Chevallard J. , Cullen F. , Finkelstein S. L. , Fontana A. , Fontanot F. , Garilli B. , Hibon P. , Koekemoer A. M. , Maccagni D. , McLure R. J. , Papovich C. , Pozzetti L. , Saxena A.
Published: September 2019

Aims. We wish to investigate the physical properties of a sample of Lyα emitting galaxies in the VANDELS survey, with particular focus on the role of kinematics and neutral hydrogen column density in the escape and spatial distribution of Lyα photons.

Methods. From all the Lyα emitting galaxies in the VANDELS Data Release 2 at 3.5 ≲ z ≲ 4.5, we selected a sample of 52 galaxies that also have a precise systemic redshift determination from at least one nebular emission line (HeII or CIII]). For these galaxies, we derived different physical properties (stellar mass, age, dust extinction, and star formation rate) from spectral energy distribution (SED) fitting of the exquisite multiwavelength photometry available in the VANDELS fields, using the dedicated spectral modeling tool BEAGLE and the UV β slope from the observed photometry. We characterized the Lyα emission in terms of kinematics, equivalent width (EW), full width at half-maximum, and spatial extension and then estimated the velocity of the neutral outflowing gas. The ultra-deep VANDELS spectra (up to 80 h on-source integration) enable this for individual galaxies without the need to rely on stacks. We then investigated the correlations between the Lyα properties and the other measured properties to study how they affect the shape and intensity of Lyα emission.

Results. We reproduce some of the well-known correlations between Lyα EW and stellar mass, dust extinction, and UV β slope, in the sense that the emission line appears brighter in galaxies with lower mass that are less dusty and bluer. We do not find any correlation with the SED-derived star formation rate, while we find that galaxies with brighter Lyα tend to be more compact in both UV and in Lyα. Our data reveal an interesting correlation between the Lyα velocity offset and the shift of the interstellar absorption lines with respect to the systemic redshift, observed for the first time at high redshifts: galaxies with higher interstellar medium (ISM) outflow velocities show smaller Lyα velocity shifts. We interpret this relation in the context of the shell-model scenario, where the velocity of the ISM and the HI column density contribute together in determining the Lyα kinematics. In support to our interpretation, we observe that galaxies with high HI column densities have much more extended Lyα spatial profiles; this is a sign of increased scattering. However, we do not find any evidence that the HI column density is related to any other physical properties of the galaxies, although this might be due in part to the limited range of parameters that our sample spans.
Molecular gas content of shell galaxies
Authors: Mancillas B. , Combes F. , Duc P.-A.
Published: September 2019

Shells are fine stellar structures that are identified by their arc-like shapes around a galaxy. They are currently thought to be vestiges of galaxy interactions and/or mergers. The study of their number, geometry, stellar populations, and gas content can help us to derive the interaction or merger history of a galaxy. Numerical simulations have proposed a mechanism of shell formation through phase wrapping during a radial minor merger. Alternatively, there could be merely a space wrapping, when particles have not yet radially oscillated, but are bound by their radial expansion, or produce an edge-brightened feature. These can be distinguished because they are expected to keep a high radial velocity. While shells are first a stellar phenomenon, HI and CO observations have revealed neutral gas associated with shells. Some of the gas, the most diffuse and dissipative, is expected to be quickly driven to the center if it is traveling on nearly radial orbits. Molecular gas, which is distributed in dense clumps, is less dissipative, and may be associated with shells. It can then determine the shell velocity, which is too difficult to obtain from stars. We present here a search for molecular gas in nine shell galaxies with the IRAM-30 m telescope. Six of them are detected in their galaxy center, and in three galaxies, we clearly detect molecular gas in shells. The derived amount of molecular gas varies from 1.5 × 108 to 3.4 × 109 M⊙ in the shells. For two of them (Arp 10 and NGC 3656), the shells are characteristic of an oblate system. Their velocity is nearly systemic, and we conclude that these shells are phase wrapped. In the third galaxy (NGC 3934), the shells appear to participate in the rotation. Follow-up with higher spatial resolution is required to conclude.
Realization of a multifrequency celestial reference frame through a combination of normal equation systems
Authors: Karbon M. , Nothnagel A.
Published: September 2019

Context. We present a celestial reference frame (CRF) based on the combination of independent, multifrequency radio source position catalogs using nearly 40 years of very long baseline interferometry observations at the standard geodetic frequencies at SX band and about 15 years of observations at higher frequencies (K and XKa). The final catalog contains 4617 sources.

Aims. We produce a multifrequency catalog of radio source positions with full variance–covariance information across all radio source positions of all input catalogs.

Methods. We combined three catalogs, one observed at 8 GHz (X band), one at 24 GHz (K band) and one at 32 GHz (Ka band). Rather than only using the radio source positions, we developed a new, rigorous combination approach by carrying over the full covariance information through the process of adding normal equation systems. Special validation routines were used to characterize the random and systematic errors between the input reference frames and the combined catalog.

Results. The resulting CRF contains precise positions of 4617 compact radio astronomical objects, 4536 measured at 8 GHz, 824 sources also observed at 24 GHz, and 674 at 32 GHz. The frame is aligned with ICRF3 within ±3 μas and shows an average positional uncertainty of 0.1 mas in right ascension and declination. No significant deformations can be identified. Comparisons with Gaia-CRF remain inconclusive, nonetheless significant differences between all frames can be attested.
Weiblicher und Männlicher Narzissmus – Gemeinsamkeiten und Unterschiede
Authors: Wardetzki Bärbel
Published: September 2019

Das Konzept des weiblichen Narzissmus 1 hat ein Bewusstsein dafür geschaffen, dass auch Frauen eine narzisstische Struktur
haben, die oft nicht erkannt wird, weil sie sich auf andere Weise äußert als die männliche. Das Modell des weiblichen Narzissmus beschreibt die seelische
Situation von Frauen mit einer starken Selbstunsicherheit, diese aber vor sich selbst und anderen verbergen und immer wieder in intimen Beziehungen
scheitern. Was bedeutet das Konzept für die psychotherapeutische Praxis?
Die ganze Welt dreht sich um mich – Narzissmus im Internet
Authors: Tränkner Johanna
Published: September 2019

In der Alltagssprache wird der Begriff „Narzissmus“ mittlerweile beinahe inflationär gebraucht – die narzisstische Persönlichkeitsstörung erscheint als
charakteristisches Krankheitsbild unserer Zeit. Der Begriff des Narzissmus, der sich eigentlich auf ein komplexes Verhaltensmuster bezieht, wird oft
missinterpretiert. Der Blick ins Internet gibt das wachsende Interesse aber auch die Komplexität des Themas wieder. Der Beitrag stellt einige der wenigen
nützlichen Webseiten zum Thema vor.
Die Geschichte der Nebenschilddrüsen
Authors: Kokenge Ferdinand
Published: September 2019

Neben der ersten anatomischen und mikroskopischen Beschreibung der Nebenschilddrüsen und ihrer Namensgebung durch Ivar Victor Sandström 1880 wird der Beitrag vieler Pathologen, Physiologen und Chirurgen in den folgenden Jahrzehnten bis zur Aufdeckung ihrer Funktion und ihrer Erkrankungen beschrieben. Eingegangen wird auf den mit einigen Irrwegen belasteten Erkenntnisgewinn zum primären Hyperparathyreoidismus, auf die erste Operation durch Felix Mandl 1925 und auf die aktuellen Therapieempfehlungen. Es schließt sich ein kurzer Abschnitt über den Hypoparathyreoidismus an.
Effect of Silver Diamine Fluoride and Proanthocyanidin on Mechanical Properties of Caries-Affected Dentin
Authors: Firouzmandi Maryam , Shafiei Fereshteh , Jowkar Zahra , Nazemi Fereshteh
Published: September 2019

Objectives Inner carious dentin is specified with decreased minerals and collagen cross-links but without protein denaturation. Current minimally invasive dentistry concepts recommend removal of only the outer layer of carious dentin and biomodification of repairable inner carious dentin. The present study aims to investigate the possibility of functional repair of this layer using silver diamine fluoride (SDF) and grape seed extract (GSE).

Materials and Methods Molar teeth with occlusal caries were used to prepare caries-affected dentin specimens for hardness and elastic modulus measurements. The specimens of each test were divided randomly into four equal groups. In the GSE group, the specimens were immersed in 6.5% GSE solution for 10 minutes. In the SDF group, the specimens underwent a topical application of a 30% SDF. In the GSE+SDF group, first the specimens were immersed in GSE and then exposed to SDF. In the SDF+GSE group, first SDF was applied and then the specimens were immersed in GSE. Microhardness measurements were taken at baseline and after treatment. A control group with distilled water treatment was also prepared for elastic modulus measurements.

Statistical Analysis One-way analysis of variance and post-hoc tests were used for statistical analysis.

Results There were significant differences in H1-H0 (final hardness—baseline hardness) among the groups. Baseline and final hardness of each group was also significantly different (SDF>SDF+GSE>GSE>GSE+SDF). Elastic modulus of SDF and SDF+GSE increased compared to the control group.

Conclusions SDF and SDF+GSE treatment can be recommended to increase hardness and elastic modulus of caries-affected dentin.
Vulvar Tuberculosis—A Rare Manifestation of the Disease
Authors: Bragança Cristina , Gonçalves Inês , Guerreiro Luísa , Janeiro Maria
Published: September 2019

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. According to data from the World Health Organization, this disease remains one of the leading causes of death worldwide. Although it most commonly affects the lungs, tuberculosis can compromise any organ. The present study reports a rare case of vulvar tuberculosis in a postmenopausal woman with a history of asymptomatic pulmonary and pleural tuberculosis, with no prior documented contact with the bacillus. Diagnosis was based on vulvar lesion biopsies, with histological findings suggestive of infection and isolation of M. tuberculosis by microbiological culture and polymerase chain reaction (PCR) essays. The lesions reverted to normal after tuberculostatic therapy.
‘When they come, we don’t send them back’: counter-narratives of ‘medical xenophobia’ in South Africa’s public health care system
Authors: Vanyoro Kudakwashe P.
Published: September 2019

Relying on the experiences of migrant patients, research on migration and health in South Africa has documented a particular concern with public health care providers as indiscriminately practicing ‘medical xenophobia’. This article argues that there is more complexity, ambivalence, and a range of possible experiences of non-nationals in South Africa’s public health care system than the current extant literature on ‘medical xenophobia’ has suggested. Based upon in-depth interviews with frontline health care providers and participant observation at a public health care clinic in Musina sub-District, this article demonstrates how discretion may play a crucial role in inclusive health care delivery to migrants in a country marred by high xenophobic sentiment. It finds that in spite of several institutional and policy-related challenges, frontline health care providers in Musina provided public health care services and HIV treatment to black African migrants who are often at the receiving end of xenophobic sentiment and violence. The article concludes that citizenship, nationality or legal status alone do not appear to tell us much as ‘bureaucratic incorporation’ and ‘therapeutic citizenship’ are some of the modalities through which migrants are constantly being (re)defined by some of South Africa’s health care providers.
Correction: Comparing apples to apples: an environmental criminology analysis of the effects of heat and rain on violent crimes in Boston
Authors: Sommer Alice J. , Lee Mihye , Bind Marie-Abèle C.
Published: September 2019

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Non-commutative probability and non-commutative processes: Beyond the Heisenberg algebra
Authors: Mendes R. Vilela
Published: September 2019

A probability space is a pair (A,ϕ) where A is an algebra and ϕ is a state on the algebra. In classical probability, A is the algebra of linear combinations of indicator functions on the sample space, and in quantum probability, A is the Heisenberg or Clifford algebra. However, other algebras are of interest in noncommutative probability. After a short review of the framework of classical and quantum probability, other noncommutative probability spaces are discussed, in particular those associated with noncommutative space-time.
Physics of efficient gridless tetrodes with intense electron beams
Authors: Appanam Karakkad Jayakrishnan , Nusinovich Gregory S. , Beaudoin Brian L. , Ting Antonio C. , Narayan Amith H. , Antonsen Thomas M.
Published: September 2019

We consider the development of a highly efficient, gridless tetrode as a megawatt-level RF source in the 3 to 10 MHz range for application in mobile ionospheric heaters. Such a heater has potential advantages over the stationary facilities, such as High-Frequency Active Auroral Research Program, found at high latitudes. The considered device operates in class D mode with an annular electron beam allowing realization of high efficiency. The present study, based on numerical simulations using the Particle in Cell code Michelle [Petillo et al., IEEE Trans. Electron Devices Sci. 52, 742 (2005)], examines the optimization of device geometry. In particular, the dependence of efficiency on spacing between electrodes is studied. In addition, the role of secondary electrons emitted at the collector is examined. Both static and time dependent operations are simulated. In the time dependent case, it is found that during the portion of the RF cycle when the beam current is on, secondaries emitted from the collector are driven back into the collector by the incoming primary beam. When the beam is switched off, secondaries can stream back into the tetrode and have a small negative impact on efficiency. We present a design in which the secondary electrons are eventually absorbed at the collector rather than at the cathode or anode.
The filamentation effect in short pulse amplification by strong-coupling stimulated Brillouin scattering
Authors: Li Zhaoli , Zuo Yanlei , Su Jingqin , Yang Suhui
Published: September 2019

The filamentation instability in strong-coupling stimulated Brillouin scattering (sc-SBS) amplification is investigated, and the growth rate and threshold power of filamentation are calculated. Theory and simulation results show that the filamentation instability destroys the amplified seed profile in sc-SBS amplification within a typical parameter region. An increase in the plasma density, which can increase the sc-SBS growth rate and avoid Raman scattering, exacerbates the filamentation instability. The relativistic effect is shown to be the main source of filamentation; however, introducing spatiotemporal incoherence into the seed pulse can greatly alleviate the filamentation instability.
Directed acyclic decomposition of Kuramoto equations
Authors: Chen Tianran
Published: September 2019

The Kuramoto model is one of the most widely studied models for describing synchronization behaviors in a network of coupled oscillators, and it has found a wide range of applications. Finding all possible frequency synchronization configurations in a general nonuniform, heterogeneous, and sparse network is important yet challenging due to complicated nonlinear interactions. From the view point of homotopy deformation, we develop a general framework for decomposing a Kuramoto network into smaller directed acyclic subnetworks, which lays the foundation for a divide-and-conquer approach to studying the configurations of frequency synchronization of large Kuramoto networks.
Strong band gap reduction in highly mismatched alloy InAlBiAs grown by molecular beam epitaxy
Authors: Zhang Jing , Wang Yuejing , Khalid Shoaib , Janotti Anderson , Haugstad Greg , Zide Joshua M. O.
Published: September 2019

We studied InAlBiAs thin films of less than 300 nm on the InP substrate with Bi composition up to 3.2%. The samples were grown by molecular beam epitaxy at low growth temperature and were shown to be fully strained to the substrate and have smooth interfaces. A bandgap reduction around 47 meV/%Bi was observed via spectroscopic ellipsometry. The valence band anticrossing model was used to fit the experimental data. The bandgaps of InAlBiAs with more than 3% Bi are much lower than the expected values from the model, which could be the result of alloy disorders.
First results from the implementation of the ITER diagnostic residual gas analyzer prototype at Wendelstein 7-X
Authors: Schlisio G. , Klepper C. C. , Harris J. H. , Biewer T. M. , Winters V. R. , Wenzel U. , Kornejew P. , Laqua H. , Krychowiak M. ,   W7-X team
Published: September 2019

Fusion reactors and long pulse fusion experiments heavily depend on a continuous fuel cycle, which requires detailed monitoring of exhaust gases. We have used a diagnostic residual gas analyzer (DRGA) built as a prototype for ITER and integrated it on the most advanced stellarator fusion experiment, Wendelstein 7-X (W7-X). The DRGA was equipped with a sampling tube and assessed for gas time of flight sample response, effects of magnetic field on gas detection and practical aspects of use in a state of the art fusion environment. The setup was successfully commissioned and operated and was used to observe the gas composition of W7-X exhaust gases. The measured time of flight gas response was found to be in the order of a second for a 7 m sample tube. High values of magnetic field were found to affect the partial pressure readings of the DRGA and suggest that additional shielding is necessary in future experimental campaigns.
Three-dimensional plasmoid-mediated reconnection and the effect of toroidal guide field in simulations of coaxial helicity injection
Authors: Ebrahimi F.
Published: September 2019

Physics of three-dimensional plasmoid-mediated magnetic reconnection during transient Coaxial Helicity Injection (CHI) plasma start-up is investigated using nonlinear MHD simulations in a spherical tokamak. We numerically examine (i) the role of three-dimensional magnetic fluctuations arising from current-sheet instabilities on the formation of plasmoid-mediated closed flux surfaces, and (ii) the effect of toroidal guide field on the MHD stability during transient CHI. We find that even in the presence of nonaxisymmetric edge magnetic fluctuations, current-carrying axisymmetric (n = 0) plasmoids are rapidly formed while twisted open field lines are being injected and are merged to form a large current-carrying magnetic bubble for plasma startup in a tokamak. It is also found that the 3-D physics response is drastically different for simulations at a higher toroidal field, and complete stabilization of nonaxisymmetric fluctuations was achieved at a higher toroidal flux.
Narrow band photoacoustic lamb wave generation for nondestructive testing using candle soot nanoparticle patches
Authors: Kim Taeyang , Chang Wei-Yi , Kim Howuk , Jiang Xiaoning
Published: September 2019

The generation of ultrasonic surface waves with a photoacoustic-laser-source has become useful for the noncontact nondestructive testing and evaluation (NDT&E) of materials and structures. In this work, a hybrid ultrasound based NDT&E method is proposed based on the photoacoustic-laser-source as a noncontact Lamb wave generator by incorporating a line-arrayed patterned candle soot nanoparticle-polydimethylsiloxane (CSNPs-PDMS) patch as the signal amplifier and with a narrow bandwidth. The CSNP-PDMS composite has been investigated as the functional patch for its laser energy absorption efficiency, fast thermal diffusion, and large thermoelastic expansion capabilities. The signal amplitude (in mW) from the CSNP-PDMS patch exhibits 2.3 times higher amplitude than the no patch condition and a narrower bandwidth than other conditions. Furthermore, improvement in the sensitivity is also achieved through the selection of the aluminum nitride sensing system. The overall combination of the Lamb wave generation and receiver-sensing system in this study is found to be very promising for a broad range of noncontact NDT&E applications.
Particle simulation studies of merging processes of two spherical-tokamak-type plasmoids
Authors: Horiuchi Ritoku , Usami Shunsuke , Moritaka Toseo , Ono Yasushi
Published: September 2019

The merging processes of spherical-tokamak-type plasmoids (STs), which are confined in a rectangular conducting vessel, are investigated by means of a two-dimensional particle-in-cell simulation. A series of simulation runs with different mass ratios clarify that a starting time of the ST merging is nearly given by a transit time for an ion sound wave to travel from an inner edge of each ST in an initial profile to a reconnection point and a part of poloidal magnetic energy is transferred to the ion thermal energy and the electron thermal energy at the approximate rate of 3:1 during the ST merging process, which is almost independent of the mass ratio except for the smallest mass ratio case of (Mi/Me) = 100. This transfer process leads to the increases in a parallel component of electron temperature and a perpendicular component of ion temperature while keeping the other components almost constant. This is because the two-component electron distribution function with different velocity shifts along a toroidal magnetic field is formed around a reconnection point when two STs merge. On the other hand, an ion distribution function, consisting of three components with different velocity shifts perpendicular to the toroidal magnetic field, is formed around the reconnection point in the merging phase. It is also found that a sharp peak appears impulsively in the electron parallel temperature profile in the merging phase, which is consistent with the Mega Ampere Spherical Tokamak merging experiments [H. Tanabe et al., Nucl. Fusion 57, 056037 (2017)].
Acceptance-cone-tunable electron spectrometer for highly-efficient constant energy mapping
Authors: Yamane Hiroyuki , Matsui Fumihiko , Ueba Takahiro , Horigome Toshio , Makita Seiji , Tanaka Kiyohisa , Kera Satoshi , Kosugi Nobuhiro
Published: September 2019

We have developed an acceptance-cone-tunable (ACT) electron spectrometer for the highly efficient constant-energy photoelectron mapping of functional materials. The ACT spectrometer consists of the hemispherical deflection analyzer with the mesh-type electrostatic lens near the sample. The photoelectron trajectory can be converged by applying a negative bias to the sample and grounding the mesh lens and the analyzer entrance. The performance of the present ACT spectrometer with neither rotating nor tilting of the sample is demonstrated by the wide-angle observation of the well-known π-band dispersion of a single crystalline graphite over the Brillouin zone. The acceptance cone of the spectrometer is expanded by a factor of 3.30 when the negative bias voltage is 10 times as high as the kinetic energy of photoelectrons.
Filament identification in wide-angle high speed imaging of the mega amp spherical tokamak
Authors: Farley T. , Walkden N. R. , Militello F. , Sanna M. , Young J. , Silburn S. S. , Harrison J. , Kogan L. , Lupelli I. , Henderson S. S. , Kirk A. , Bradley J. W.
Published: September 2019

A new tomographic inversion technique is presented for the identification of plasma filaments in wide-angle visible camera data. The technique works on the assumption that background subtracted images of filaments can be represented as a superposition of uniformly emitting magnetic equilibrium field lines. A large collection of equilibrium magnetic field lines is traced and projected onto the camera field of view and combined to form a geometry matrix describing the coordinate transformation from magnetic field aligned coordinates to image pixel coordinates. Inverting this matrix enables the reprojection of the emission in the camera images onto a field aligned basis, from which filaments are readily identifiable. The inversion is a poorly conditioned problem which is overcome using a least-squares approach with Laplacian regularization. Blobs are identified using the “watershed” algorithm and 2D Gaussians are fitted to get the positions, widths, and amplitudes of the filaments. A synthetic camera diagnostic generating images containing experimentally representative filaments is utilized to rigorously benchmark the accuracy and reliability of the technique. 74% of synthetic filaments above the detection amplitude threshold are successfully detected, with 98.8% of detected filaments being true positives. The accuracy with which filament properties and their probability density functions are recovered is discussed, along with sources of error and methods to minimize them.
An alternative method to study cross-flow instabilities based on high order dynamic mode decomposition
Authors: Le Clainche Soledad , Han Zhong-Hua , Ferrer Esteban
Published: September 2019

We present a novel method for the determination of N-factors in cross-flow transition scenarios. The method considers numerical simulations, in which a turbulent model is applied downstream from a predetermined point and solves a laminar flow upstream from this point. The solution is postprocessed using higher order dynamic mode decomposition to extract the leading spatial mode in several small sections along the streamwise direction. The spatial evolution of the amplitude of this mode will determine the N-factor. The results presented are compared with experimental measurements and linear stability theory, showing the good performance of this novel method, which does not assume parallel flow assumptions, is automatic and computationally efficient.
Unsteady effects of periodic wake passing frequency on aerodynamic performance of ultra-high-lift low pressure turbine cascades
Authors: Qu Xiao , Zhang Yanfeng , Lu Xingen , Zhu Junqiang
Published: September 2019

Flow losses and flow field data downstream of an ultra-high-lift aft-loaded low pressure turbine cascade were comprehensively measured for different incoming wake passing frequencies, and the mechanisms through which incoming wakes influence secondary flow were examined via numerical calculations. Reynolds numbers ranging from 25 000–100 000 (based on the axial chord and inlet velocity) were considered in both the presence and absence of the wakes. At low Reynolds numbers of 25 000 and 50 000, increasing wake passing frequency gradually suppressed the suction surface separation bubble and increased the cross-passage pressure gradient, and the unsteady wakes clearly improved the throughflow characteristics of the cascade passage. Furthermore, the larger separation bubble on the suction surface hindered the migration of the secondary vortices from the endwall to span. Consequently, incoming wakes were not beneficial for suppressing secondary flow at low Reynolds numbers. At the high Reynolds numbers of 80 000 and 100 000, increasing wake passing frequency afforded stronger inhibition of the secondary flow owing to the reduction in blade loading originating from the “negative jet” influence of the wakes. Transport of incoming wakes in the cascade passage caused the downstream migration of the position of the saddle point, which is also advantageous for decreasing secondary flow losses.
Large-scale azimuthal structures in Hall-type plasma discharges
Authors: Marusov N. A. , Sorokina E. A. , Ilgisonis V. I. , Lakhin V. P.
Published: September 2019

An explanation of large-scale low-frequency oscillations observed by means of a high-speed camera in different Hall-type plasma devices (magnetrons, Penning discharges, Hall thrusters, etc.) is proposed. They can be interpreted as the beating between high-frequency eigenmodes of gradient drift instability occurring in spatially bounded nonuniform plasmas. The resemblance of the experimental data obtained with the finite exposure time and the calculated characteristics of high-frequency modes beating is highlighted. The main results are obtained analytically in a magnetron-like configuration with the axial magnetic field and the radial electric field.
Structural, band and electrical characterization of β-(Al0.19Ga0.81)2O3 films grown by molecular beam epitaxy on Sn doped β-Ga2O3 substrate
Authors: Vaidya Abhishek , Sarker Jith , Zhang Yi , Lubecki Lauren , Wallace Joshua , Poplawsky Jonathan D. , Sasaki K. , Kuramata A. , Goyal Amit , Gardella Joseph A. , Mazumder Baishakhi , Singisetti Uttam
Published: September 2019

We characterized unintentionally doped β-(Al0.19Ga0.81)2O3 for its structural, band, and electrical properties by using a variety of material and electrical characterization methods such as atom probe tomography (APT), transmission electron microscope, X-ray photoelectron spectroscopy (XPS), capacitance-voltage measurement, and a temperature dependent forward current-voltage measurement. A 115 nm thick β-(Al0.19Ga0.81)2O3 film was grown by molecular beam epitaxy on Sn doped Ga2O3 substrates. Reciprocal space mapping shows a lattice matched (Al0.19Ga0.81)2O3 layer. Both APT and TEM results confirm a sharp β-(Al0.19Ga0.81)2O3/β-Ga2O3 interface. XPS measurements show conduction band offsets of 2.78 ± 0.25 eV and 0.79 ± 0.25 eV between the SiO2/β-(Al0.19Ga0.81)2O3 and β-(Al0.19Ga0.81)2O3/β-Ga2O3 interfaces, respectively. Extracted room temperature Schottky Barrier Heights (SBHs) after zero field correction for Pt, Ni, and Ti were 2.98 ± 0.25 eV, 2.81 ± 0.25 eV, and 1.81 ± 0.25 eV, respectively. The variation of SBHs with metals clearly indicates the dependence on work function.