bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-monotonic threshold voltage variation in 4H-SiC metal–oxide–semiconductor field-effect transistor: Investigation and modeling
Authors: Masin F. , De Santi C. , Lettens J. , Franchi J. , Domeij M. , Moens P. , Meneghini M. , Meneghesso G. , Zanoni E.
Published: October 2021

We propose an analytical model to reproduce the non-monotonic instability of the threshold voltage in 4H-SiC MOSFETs submitted to a positive gate stress bias. Experimental analysis of the threshold voltage transients indicates that both electron and hole trappings take place in the gate dielectric or at the dielectric/semiconductor interface, responsible for a VTH increasing–decreasing–increasing pattern. At low/moderate stress fields (<7 MV/cm), the electron trapping kinetics responsible for a positive VTH shift are modeled by a rate equation considering a trapping-inhibition model, which explains the logarithmic degradation kinetics. In the high field regime (>8 MV/cm), we propose that electrons can tunnel through the SiO2, be accelerated by the high field, and generate holes through impact ionization (II) or anode hole injection. These holes are then trapped in the oxide, thus generating a negative VTH shift. This second process has an exponential time-dependency, as found through the analysis of the corresponding rate equations. The time constant of the positive VTH shift is evaluated as a function of stress voltage and temperature. The results indicate that the time constant is strongly dependent on the electric field (that accelerates electrons to generate holes), and not thermally activated, in agreement with theoretical considerations.
Depletion torques between anisotropic colloidal particles
Authors: Mason Thomas G.
Published: October 2021

We explore how the entropic notion of depletion forces between spheres, introduced by Asakura and Oosawa, can be extended to depletion torques that affect the orientations of colloidal particles having complex shapes. In prior experimental work, systems of microscale plate-like particles in the presence of a nanoscale depletion agent have been shown to form polymer-like columnar chains; restoring depletion torques act to align lithographically-structured platelets within a chain orientationally about the chain’s axis. We consider depletion torques corresponding to parallel, face-to-face, near-contact pair interactions for complex-shaped, plate-like, prismatic lithographic particles in colloidal dispersions containing a spherical nanoscale depletion agent. We calculate depletion torques for a wide variety of such particles, including rotationally symmetric, asymmetric, achiral, chiral, and elongated particles. Moreover, we determine depletion torques between two non-parallel proximate square platelets connected by a lossless hinge along a common edge. Our investigations show that depletion torques can be tailored through lithographic or synthetic design of specific geometrical features in the shapes of particles.
Electro-optically derived millimeter-wave sources with phase and amplitude control
Authors: Bosworth Bryan T. , Jungwirth Nick R. , Smith Kassiopeia , Cheron Jerome , Quinlan Franklyn , Woodson Madison , Morgan Jesse , Beling Andreas , Feldman Ari , Williams Dylan , Orloff Nathan D. , Long Christian J.
Published: October 2021

Integrated circuits are building blocks in millimeter-wave handsets and base stations, requiring nonlinear characterization to optimize performance and energy efficiency. Today's sources use digital-to-analog converters to synthesize arbitrary electrical waveforms for nonlinear characterization, but this approach demands even faster integrated circuits to increase the bandwidth to millimeter-waves. Optically derived sources are a potential path to generate precise millimeter-waves and arbitrary waveforms using additive frequency synthesis. In this work, we demonstrate optically derived millimeter-waves up to 99.2 GHz with phase and amplitude control that could be locked to an optical reference. Our approach uses a 1550 nm electro-optic frequency comb with a terahertz of bandwidth. A programmable spectral filter selects two wavelengths from the optical comb, illuminating a modified uni-traveling carrier photodiode on a coplanar waveguide. We then tune the phase and amplitude by varying the optical phase and amplitude in the programmable spectral filter. The result of our work is electro-optically derived millimeter-waves at (24.8, 49.6, 74.4, and 99.2) GHz with phase and amplitude control, enabling arbitrary repetitive waveform generation.
Photothermal actuation of levitated pyrolytic graphite revised
Authors: Yee Steven , Oney Louisa , Cosby Tyler , Durkin David P. , ElBidweihy Hatem
Published: October 2021

The significant diamagnetism of pyrolytic graphite (PyG) allows it to be passively levitated above permanent magnet arrays and translated in the plane of these arrays via optical irradiation, which promotes applications in frictionless milli-scale robotics. Previous explanations for the translation effect have cited photothermal heating of levitated PyG and the thermal dependence of PyG’s magnetic susceptibility, as observed through measurements of samples at uniform temperatures. In this article, we offer a revision to the theory of photothermal actuation of levitated PyG. Through experiments and simulations, we demonstrate that the gradient of PyG’s diamagnetism with temperature—as measured for samples at uniform temperatures—is insufficient to explain the magnitude of forces required by the optically induced translation phenomenon. We hypothesize that the contrast in diamagnetism of PyG samples under asymmetric photothermal heating is at least an order of magnitude greater than that expected from measurements where the sample temperature is uniformly varied. We propose that the origin of the enhanced diamagnetic contrast under asymmetric optical irradiation is a photothermoelectric effect, which impacts the concentration of electrons in diamagnetically significant orbital states in graphite. To support this hypothesis, we take qualitative measurements, demonstrating the n-type thermoelectricity of PyG samples under optical irradiation while also characterizing the graphitic material with scanning electron microscopy/energy dispersive x-ray spectroscopy. We highlight the new understanding of the origin of the photothermal actuation through experiments using PyG samples with modified geometries that exhibit a pronounced preference in the axis of translation.
Molecular design of two-dimensional perovskite cations for efficient energy cascade in perovskite light-emitting diodes
Authors: Jamaludin Nur Fadilah , Febriansyah Benny , Ng Yan Fong , Yantara Natalia , Li Mingjie , Giovanni David , Fu Jianhui , Tay Yeow Boon , Baikie Tom , Sum Tze Chien , Mathews Nripan , Mhaisalkar Subodh
Published: October 2021

Despite extensive reports on highly efficient perovskite light-emitting diodes, rules governing the design of suitable two-dimensional (2D) perovskite templating cation to facilitate formation of optimal emitter landscape for energy cascade remain largely elusive. With factors such as structure, size, functionalization, and charge capable of influencing the distribution of multidimensional perovskite phases, the importance of 2D templating cation design in determining film optoelectronic properties is indisputable. However, typical mono-functionalized 2D templating cations often result in larger lead halide octahedral spacing, which impedes effective charge transport. This has fueled investigation into the use of multiple cations for optimal domain distribution and improved charge transfer kinetics to the emitting species. In this study, we attempt to impart enhanced charge transfer characteristics to the resultant multidimensional perovskite by employing two bi-functionalized aromatic cations, namely, pyridinium ethyl ammonium and imidazolium ethyl ammonium, reminiscent of mono-functionalized phenyl ethyl ammonium, a widely used 2D perovskite templating cation. Although it is proposed that greater intermolecular bonding would enhance charge transfer rates, the simultaneous increase in lead halide octahedral distortion results in quenching of their corresponding 2D and multidimensional perovskite luminescence properties, correlated with increased defect density within the material. This manifests in the form of shorter PL decay lifetimes, lower PLQY, and device performance arising from inferior energy funneling. This study highlights the importance of designing 2D perovskite templating cations offering better transport and reduced octahedral distortion for the development of energy cascade-efficient, multidimensional perovskites.
Relaxation behavior of nonvolatile resistance modulation in Zn:SnO2/PMN-PT heterostructures
Authors: Wang Yue , Jin Chao , Wang Ping , Bai Haili
Published: October 2021

Relaxation in resistance switching (RS) has severely hindered the stability of memory devices based on oxide-thin-film/ferroelectric heterostructures. In this work, Zn doped SnO2 (ZTO) thin films were deposited on (111)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) substrates to investigate the effect of oxygen vacancies (OVs) on resistance relaxation. The polarization-dependent resistance relaxation is observed in ZTO/PMN-0.3PT heterostructures. The largest relative change in resistance up to 53.6% within 20 min is ascribed to OV diffusion. Local aggregation of positively charged OVs with the application of poling electric field would enhance the Coulomb repulsion and strain in distorted lattice, which could accelerate the OV back-diffusion. Partial positively charged OVs are neutralized in the positive polarization state with the application of +10 kV/cm poling voltage, which weakens the relaxation compared to the negative polarization state. Our work helps to understand the interrelation between OVs and polarization-dependent relaxation of RS properties.
Current leakage mechanisms related to threading dislocations in Ge-rich SiGe heterostructures grown on Si(001)
Authors: Tetzner H. , Fischer I. A. , Skibitzki O. , Mirza M. M. , Manganelli C. L. , Luongo G. , Spirito D. , Paul D. J. , De Seta M. , Capellini G.
Published: October 2021

This work investigates the role of threading dislocation densities (TDD) in the low density regime on the vertical transport in Si0.06Ge0.94 heterostructures integrated on Si(001). The use of unintentionally doped Si0.06Ge0.94 layers enables the study of the impact of grown-in threading dislocations (TD) without interaction with processing-induced defects originating, e.g., from dopant implantation. The studied heterolayers, while equal in composition, the degree of strain relaxation, and the thickness feature three different values for the TDD as 3 × 106, 9 × 106, and 2 × 107 cm−2. Current–voltage measurements reveal that leakage currents do not scale linearly with TDD. The temperature dependence of the leakage currents suggests a strong contribution of field-enhanced carrier generation to the current transport with the trap-assisted tunneling via TD-induced defect states identified as the dominant transport mechanism at room temperature. At lower temperatures and at high electric fields, direct band-to-band tunneling without direct interactions with defect levels becomes the dominating type of transport. Leakage currents related to emission from mid-gap traps by the Shockley–Read–Hall (SRH) generation are observed at higher temperatures (>100 °C). Here, we see a reduced contribution coming from SRH in our material, featuring the minimal TDD (3 × 106 cm−2), which we attribute to a reduction in point defect clusters trapped in the TD strain fields.
Effects of many-body interactions on the transient optical properties of lead halide perovskites
Authors: Xiang Guangbiao , Wu Yanwen , Miao Xiaona , Li Yushuang , Leng Jiancai , Wu Bo , Cheng Chuanfu , Ma Hong
Published: October 2021

Lead halide perovskites (LHPs) are emerging as promising candidates for use in various high-performance optoelectronic applications, yet their photophysics remains a topic of debate. Here, we theoretically investigated how the ultrafast optical properties of a few prototype LHPs are affected by many-body interactions, including the bandgap renormalization (BGR) effect, the band-filling (BF) effect, the free-carrier absorption effect, and the exciton effect, at carrier densities ranging from 1016 to 1019 cm−3. The results show that the exciton absorption becomes more obvious near the bandgap with increasing exciton energy (as the halogen component of the LHP is varied from I to Cl). Transient reflectivity results indicate that the signal has one peak below the bandgap as a result of the BGR effect at low carrier densities and one valley above the bandgap originating from the BF effect at high carrier densities. In addition, the absorbance decreases with increasing the carrier density as a result of the BF effect because the filled energy levels are observed at 2 meV above the bottom of the conduction band. The results of the present work are expected to promote the application of LHPs in solar cells, light-emitting diodes, and other photoelectric devices.
Enhanced local viscosity around colloidal nanoparticles probed by equilibrium molecular dynamics simulations
Authors: Rabani Reza , Saidi Mohammad Hassan , Joly Laurent , Merabia Samy , Rajabpour Ali
Published: October 2021

Nanofluids—dispersions of nanometer-sized particles in a liquid medium—have been proposed for a wide variety of thermal management applications. It is known that a solid-like nanolayer of liquid of typical thicknesses of 0.5–1 nm surrounding the colloidal nanoparticles can act as a thermal bridge between the nanoparticle and the bulk liquid. Yet, its effect on the nanofluid viscosity has not been elucidated so far. In this article, we compute the local viscosity of the nanolayer using equilibrium molecular dynamics based on the Green–Kubo formula. We first assess the validity of the method to predict the viscosity locally. We apply this methodology to the calculation of the local viscosity in the immediate vicinity of a metallic nanoparticle for a wide range of solid–liquid interaction strength, where a nanolayer of thickness 1 nm is observed as a result of the interaction with the nanoparticle. The viscosity of the nanolayer, which is found to be higher than its corresponding bulk value, is directly dependent on the solid–liquid interaction strength. We discuss the origin of this viscosity enhancement and show that the liquid density increment alone cannot explain the values of the viscosity observed. Rather, we suggest that the solid-like structure of the distribution of the liquid atoms in the vicinity of the nanoparticle contributes to the nanolayer viscosity enhancement. Finally, we observe a failure of the Stokes–Einstein relation between viscosity and diffusion close to the wall, depending on the liquid–solid interaction strength, which we rationalize in terms of the hydrodynamic slip.
Metalorganic chemical vapor deposition of α-Ga2O3 and α-(AlxGa1−x)2O3 thin films on m-plane sapphire substrates
Authors: Bhuiyan A F M Anhar Uddin , Feng Zixuan , Huang Hsien-Lien , Meng Lingyu , Hwang Jinwoo , Zhao Hongping
Published: October 2021

Single α-phase (AlxGa1−x)2O3 thin films are grown on m-plane sapphire (α-Al2O3) substrates via metalorganic chemical vapor deposition. By systematically tuning the growth parameters including the precursor molar flow rates, chamber pressure, and growth temperature, the epitaxial growth of high-quality phase pure α-(AlxGa1−x)2O3 films (0 ≤ x ≤ 1) is demonstrated with smooth surface morphologies and alloy homogeneities by comprehensive material characterization. The asymmetrical reciprocal space mapping reveals fully relaxed films for α-(AlxGa1−x)2O3 films with x ≤ 0.5. The coherent growth of α-(AlxGa1−x)2O3/α-Al2O3 superlattice structures is demonstrated with abrupt interfaces and uniform Al distribution for higher Al compositions at x = 0.78 in the α-(AlxGa1−x)2O3 layer. The influence of growth parameters, such as growth temperature and chamber pressure, on the phase stabilization and Al incorporation in the α-(AlxGa1−x)2O3 films is investigated. While lower growth temperatures facilitate the phase stabilization of α-Ga2O3 thin films, lower chamber pressure leads to higher Al incorporation in α-(AlxGa1−x)2O3 films. High resolution x-ray photoelectron spectroscopy was utilized for determining the Al compositions and bandgaps of α-(AlxGa1−x)2O3. Furthermore, the evolution of the valance and conduction band offsets at α-Al2O3/α-(AlxGa1−x)2O3 heterojunctions is evaluated with the variation of Al compositions, which reveals the formation of type-I (straddling) band alignment between α-Al2O3 and α-(AlxGa1−x)2O3.
A fast and efficient tool to study the rheology of dense suspensions
Authors: Monti Alessandro , Rathee Vikram , Shen Amy Q. , Rosti Marco E.
Published: October 2021

A cutting-edge software that adopts an optimized searching algorithm is presented to tackle the Newton–Euler equations governing the dynamics of dense suspensions in Newtonian fluids. In particular, we propose an implementation of a fixed-radius near neighbors search based on an efficient counting sort algorithm with an improved symmetric search. The adopted search method drastically reduces the computational cost and allows an efficient parallelization even on a single node through the multi-threading paradigm. Emphasis is also given to the memory efficiency of the code since the history of the contacts among particles has to be traced to model the frictional contributions, when dealing with dense suspensions of rheological interest that consider non-smooth interacting particles. An effective procedure based on an estimate of the maximum number of the smallest particles surrounding the largest one (given the radii distribution) and a sort applied only to the surrounding particles only is implemented, allowing us to effectively tackle the rheology of non-monodispersed particles with a high size-ratio in large domains. Finally, we present validations and verification of the numerical procedure, by comparing with previous simulations and experiments, and present new software capabilities.
Evolution mechanism of a prototype pump turbine after pump power-off
Authors: Li Deyou , Fu Xiaolong , Wang Hongjie , Zhao Rundong , Wei Xianzhu
Published: October 2021

This study aimed to analyze the time–frequency characteristics of pressure fluctuations and reveal their underlying flow mechanisms during the unavoidable guide vane closing process after a pump power-off in a pumped-storage hydropower plant. In this study, the weak compressibility model, one- and three-dimensional (1D–3D) coupling simulation method, and dynamic mesh technology were adopted simultaneously to accurately simulate the transient flow in a prototype pump turbine during the guide vane closure process after the pump power-off. According to the analysis results of the short-time Fourier transformation for the pressure fluctuations, apart from the familiar runner blade passing frequency and its harmonics, this study found a new component that is five times the runner rotation frequency as well as components that are lower than 4.5 times the runner rotation frequency and correspond to severe fluctuations in the pressure. Internal flow analysis suggests that the former is induced by unstable vortices near the trailing edges of the runner blades, whereas the latter ones are induced by local backflow vortices near the runner inlet. Additionally, these severe pressure fluctuation components were significantly large closer to the maximum reverse discharge of the pump brake mode. This finding indicates that these severe unsteady pressure fluctuation components can be suppressed by optimizing the reduction in the maximum reverse discharge in the pump brake mode.
Combining machine learning and data assimilation to forecast dynamical systems from noisy partial observations
Authors: Gottwald Georg A. , Reich Sebastian
Published: October 2021

We present a supervised learning method to learn the propagator map of a dynamical system from partial and noisy observations. In our computationally cheap and easy-to-implement framework, a neural network consisting of random feature maps is trained sequentially by incoming observations within a data assimilation procedure. By employing Takens’s embedding theorem, the network is trained on delay coordinates. We show that the combination of random feature maps and data assimilation, called RAFDA, outperforms standard random feature maps for which the dynamics is learned using batch data.
Vertical GaN p+-n junction diode with ideal avalanche capability grown by halide vapor phase epitaxy
Authors: Ohnishi Kazuki , Kawasaki Seiya , Fujimoto Naoki , Nitta Shugo , Watanabe Hirotaka , Honda Yoshio , Amano Hiroshi
Published: October 2021

A vertical GaN p+-n junction diode with an ideal breakdown voltage was grown by halide vapor phase epitaxy (HVPE). A steep p+-n interface was observed even with the use of the HVPE method. No Si-accumulating layer was formed at the p+-n interface because of the continuous HVPE growth from the n-type drift layer to the p-type layer. This method provides improved electrical properties compared with the regrowth of p-type GaN layers. The minimum ideality factor of approximately 1.6 was obtained. The breakdown voltage increased from 874 to 974 V with the increase in the temperature from 25 to 200 °C, which suggests that avalanche multiplication causes the breakdown. The temperature-dependent breakdown voltage was in good agreement with the breakdown voltage calculated using the ideal critical electric field. These results indicate that HVPE is promising for the fabrication of vertical GaN power devices.
Pressure reconstruction of a planar turbulent flow field within a multiply connected domain with arbitrary boundary shapes
Authors: Liu Xiaofeng , Moreto Jose Roberto
Published: October 2021

This paper reports for the first time the implementation procedures and validation results for pressure reconstruction of a planar turbulent flow field within a multiply connected domain that has arbitrary inner and outer boundary shapes. The pressure reconstruction algorithm used in this study is the rotating parallel-ray omni-directional integration algorithm that offers high-level of accuracy in the reconstructed pressure. While preserving the nature and advantage of the parallel ray omni-directional pressure reconstruction at places with flow data, the new implementation of the algorithm is capable of processing an arbitrary number of inner void areas with arbitrary boundary shapes. Validation of the multiply connected domain pressure reconstruction code is conducted using the Johns Hopkins DNS (Direct Numerical Simulation) isotropic turbulence databases [J. Graham et al., J. Turbul. 17(2), 181 (2016)], with 1000 statistically independent pressure gradient field realizations embedded with random noise used to gauge the code performance. For further validation, the code is also applied for pressure reconstruction from the DNS data [E. Johnsen and T. Colonius, J. Fluid Mech., 629, 231 (2009)] about a shock-induced non-spherical bubble collapse in water. It is demonstrated that the parallel-ray omni-directional integration algorithm outperforms the Poisson equation approach in terms of the accuracy for the pressure reconstruction from error embedded pressure gradients in both simply connected and multiply connected domains.
Self-powered solar-blind α-Ga2O3 thin-film UV-C photodiode grown by halide vapor-phase epitaxy
Authors: Bae Jinho , Park Ji-Hyeon , Jeon Dae-Woo , Kim Jihyun
Published: October 2021

A compact self-powered solar-blind UV-C photodiode was demonstrated using an ultra-wide bandgap (UWBG) α-Ga2O3 thin film as a wavelength-selective absorber layer. The UWBG-based Schottky junction architecture renders the use of low-performance and bulky solar-blind UV bandpass filters unnecessary. High-quality α-Ga2O3 thin films with a thickness of 1.25 µm were grown on a (0001) sapphire substrate via the halide vapor-phase epitaxy technique. The self-powered solar-blind UV-C photodetector based on the Ni/α-Ga2O3 Schottky junction exhibited excellent responsivity (1.17 × 10−4 A/W), photo-to-dark current ratio (1.12 × 105), and reproducibility, as well as fast rise/decay characteristics without persistent photoconductivity upon exposure to UV-C radiation (254 nm wavelength). The relationship between light intensity (I) and photocurrent (P) was modeled by I ∼ P0.69, indicating the high-quality of the halide vapor-phase epitaxy-grown α-Ga2O3 thin film. Upon exposure to natural sunlight, the fabricated solar-blind photodetector showed excellent solar blindness with sensitivity to UV-C radiation and did not require an external power source. Therefore, this UWBG α-Ga2O3 thin-film Schottky barrier photodiode is expected to facilitate the development of a compact and energy-independent next-generation UV-C photodetector with solar blindness.
Simultaneous impact of twin drops on a semi-infinite liquid target
Authors: Artman-Breitung Madison , Watson Daren A. , Dickerson Andrew K.
Published: October 2021

We take the enduring topic of drop impact on a deep pool of similar liquid further by allowing twin drops to impact simultaneously. Impacts are sufficiently proximal that impact crowns and craters interact, distorting and merging craters, and creating previously undocumented supersurface fluid interactions. The unique features of twin impacts occur when crowns collide to create a central veil that bifurcates the two craters and the expulsion of jet-like features atop colliding crowns. The emergence of a plethora of splash features is dependent on the Froude number (Fr=30−200) and drop separation distance. We analyze proximal crater evolution using theory developed for singular drops and develop scaling relations to predict crown and jet height. Crater and jet energies are compared for various impact velocities and drop separation distances. We find that craters close enough to merge produce thicker, but not higher, rebound jets.
Explicit versus non-explicit prosodic training in the learning of Spanish L2 stress contrasts by French listeners
Authors: Schwab Sandra , Dellwo Volker
Published: October 2021

Different methods to acquire a language can contribute differently to learning success. In the present study we tested the success of L2 stress contrasts acquisition, when ab initio learners were taught or not about the theoretic nature of L2 stress contrasts. In two 4-hour perceptual training methods, French-speaking listeners received either (a) explicit instructions about Spanish stress patterns and perception activities commonly used in L2 pronunciation courses or (b) no explicit instructions and a unique perception activity, a shape/word matching task. Results showed that French-speaking listeners improved their ability to identify and discriminate stress contrasts in Spanish after training. However, there was no significant difference between explicit and non-explicit training nor was there an effect on stress processing under different phonetic variability conditions. This suggests that in L2 stress acquisition, non-explicit training may benefit ab initio learners as much as explicit instruction and activities used in L2 pronunciation courses.
Learner translation of metaphor
Authors: Nacey Susan , Skogmo Siri Fürst
Published: October 2021

This article explores metaphor translation strategies of novice translators: university students translating from L1 Norwegian to L2 English. We first describe the translation strategies they employ in their translated texts, thereby offering evidence of what translators do with metaphor based on multiple translations of the same metaphor-dense source text. We then go beyond this descriptive analysis to discuss why these translators make their particular choices, analyzing the students’ in-class discussion and individual written reflections about their translations. We thus illuminate the challenges that the novice translators consciously perceive (that is, is metaphor a problem?), as well as their motivation for and evaluation of their translation solutions. In this way, we shed light on the concept of the ‘successful’ translation of metaphor.
The relationship between topic and metaphor in second-language learners’ essays
Authors: Golden Anne
Published: October 2021

In this article I investigate to what extent the use of metaphorical expressions in language learners’ texts vary according to the topic they have chosen to write about. The data come from the Norwegian learner corpus ASK, where the texts are from written assignments produced by adult second-language learners as part of an official Norwegian test and texts. Texts from two different prompts are selected, which are related to friendship and nature. Metaphors are defined according to conceptual metaphor theory and a triangulation of methods is used, alternating between a manual and an automatic extraction method.

The results confirm the hypothesis that the two different prompts given to the learners in a language test not only triggers different metaphorical expressions but also influences the amount of metaphor used in the learners’ writing. This knowledge is important to researchers for comparing the use of metaphors between different groups, such as between different learners or between students in different stages of education. It is also important for test designers who decide on topics to be used in tests and teachers who help learners prepare for their tests. In addition, it is of interest for researchers, educators in general and the learners themselves who are interested in the effect the use of metaphors in texts have on raters’ evaluations in high-stake tests.
Answering the charge?
Authors: Askeland Norunn
Published: October 2021

From 1850 to 1980 the Norwegian state pursued a policy of Norwegianization of the Sami, where schools played an important part in the attempt to turn Sami children into Norwegian citizens. Pupils lived in boarding schools where all teaching was in Norwegian and it was forbidden to speak Sami, both in and out of the classroom. This article examines metaphors in three types of material: Norwegian textbooks; Sami literature in these textbooks; and Sami testimony literature. The aim is to find out how the Norwegian state used its power to stigmatize Sami identity through metaphors in textbooks, and how Sami writers show their resistance to Norwegianization through metaphors in Sami literary texts and Sami testimony literature. The analysis also examines whether metaphors are signalled or not, in order to see if they are open to negotiation or taken as self-evident, and if signalling can be related to genre. One central finding is that the Norwegian texts contain more condescending and less signalled metaphors than the Sami ones. Another is that signalling might be related to genre: there are more signalled metaphors in the reflective narratives of witness testimonies than in the other genres that are examined. The theoretical foundations of the analyses are discourse-based metaphor analysis in a post-colonial perspective.
785 Is Subspecialisation Important for The Emergency Laparotomy Outcomes?
Authors: Chowdhury S , Musbahi A , Agarwal A
Published: October 2021

Introduction

High mortality and morbidity is associated with Emergency Laparotomy. This study looks at outcomes of different subspecialties of surgeons performing Emergency Laparotomies identified from National Emergency Laparotomy Audit (NELA).

Method

Results

Conclusions
1026 Assessing the Reliability of 3D Imaging for Wound Measurements
Authors: Hitchman L , Cai P , Sethi S , Stirrup A , Lathan R , Sidapra M , Smith G , Carradice D , Chetter I
Published: October 2021

Aim

To investigate the inter and intra reliability of using 3D imaging to measure wounds.

Method

20 wound models of 4 different shaped wounds in 5 different colours were created from plastic mouldable beads. 3D images were taken using the BlasterX Senz3D camera and measured using the GPC Wound Measure application (version 3.15.0.0, UK). Intra-user reliability was determined comparing 20 wound measurements of each wound model. Inter-user reliability was determined by 5 different clinicians photographing each model and independently measuring each wound photo. The inter- and intra-rater measurements for wound surface area and volume were compared using the ICC and differences from the overall mean plotted on Bland-Altman graphs.

Results

The interclass co-efficient (ICC) for inter-rater reliability in measuring surface area was 0.958 (95% CI 0.919-0.981, p < 0.005). The intra-rater reliability when measuring wound surface area was 0.996 (95% CI 0.993-0.998, p < 0.005). For wound volume, the ICC for inter-rater reliability was 0.925 (95% CI 0.857-0.967, p < 0.005) and 0.999 (95% CI 0.998-0.999, p < 0.005) for intra-user reliability. 5.5% of measurements were outside 2 SD of the mean for wound volume.

Conclusions

3D imaging offers a quick, reliable, and easy to use solution to measuring wounds. We have shown it is a reliable and reproducible method of measuring wounds between different clinicians.
1039 Assessing the Efficacy of The Modified S-PECS Anaesthetic Block in Patients Undergoing Breast Augmentation Surgery – A Randomised Double-Blind Control Trial
Authors: Saghir R , Saghir N , Okhiria R , Okhiria T , Sidhu M , Husein R , Sforza M
Published: October 2021

Aim

Postoperative acute on chronic pain following breast surgery is a common complication which needs resolving to allow for improved patient outcomes. Previously thoracic epidurals and paravertebral blocks (PVB) have been the gold standard administered intra-operatively. However, more recently the introduction of the Pectoral nerve block (PECS and PECS-2 blocks) has looked promising to control the pain more effectively, but further robust analysis is required to prove its efficacy. The authors aim to study the efficacy of a new block S-PECS that comprises a serratus anterior and a PECS-2 block associated.

Method

In this study we performed a prospective, single-centre randomised controlled double-blind group trial in 30 female patients undergoing breast augmentation surgery with silicone breast implants and the S-PECS block. Divided into groups of 15, the S-PECS group received local anaesthetics with the no-PECS control group receiving a saline injection. All participants were followed up at recovery (REC), 4, 6 and 12 (4H, 6H and 12H) hourly postoperatively.

Results

Our results showed that the pain score in the S-PECS group was significantly less than the no-PECS group across all time points REC, 4H, 6H and 12H. Furthermore, the patients that received the S-PECS block were 74% less likely to request pain medications compared to the no-PECS group (p < 0.05).

Conclusions

Overall, the modified S-PECS block is an effective, efficient, and safe method of controlling pain in patients undergoing breast augmentation surgery with additional applications yet to be explored.
1609 Patient Demographics and Outcomes Following Acute Presentation with An Inguinal Hernia; A 15-Year Retrospective Cohort Study from The North of England
Authors: Clyde D , Li L , Swan R , McLean R , Brown L
Published: October 2021

Aim

Although inguinal hernia repair is one of the most common elective procedures performed, emergency repair carries a far greater risk to patients. This study aimed to report on patient demographics and outcomes following emergency presentation with an inguinal hernia.

Method

Patients ≥18 years admitted acutely with an inguinal hernia across NHS trusts in the North of England between 2002-2016 were identified. Data were collected on demographics, investigations, and operative interventions. Outcomes including length of stay (LoS) and 30-day mortality were analysed.

Results

A total of 4698 patients presented over the 15-year study period. The cohort were predominantly male (n = 4133, 88.0%) with median age of 71 years (IQR: 56-81). Whilst no significant difference in age or gender were found across the study period, comorbidities, as measured by Charlson score, increased over time (p < 0.001). In those who underwent operative intervention (n = 2580), median length of stay was 3 days (IQR: 2-5) and 30-day inpatient mortality rate was 2.5%. Advanced age and comorbidity were associated with higher overall 30-day mortality and post-operative 30-day mortality (both p < 0.001).

Conclusions

This study highlights the frailty of patients presenting as emergency with complications secondary to inguinal hernia. Given the increased risk observed in this patient group, it is vital that perioperative care is optimised, and patients are counselled appropriately.
1095 The Utility of Plasma Circulating Cell-Free Messenger RNA as A Biomarker of Glioma: A Pilot Study
Authors: Ita M , Wang J H , Toulouse A , Lim C , Fanning N , O’Sullivan M , Nolan Y , Kaar G , Redmond H
Published: October 2021

Introduction

Research into the potential utility of plasma-derived circulating-cell-free nucleic acids as non-invasive adjuncts to radiological imaging has been occasioned by the invasive nature of brain tumour biopsy. Circulating-cell-free messenger RNAs are short fragments of RNA present in blood. The objective of this study was to determine whether significant differences exist in the plasma transcriptomic profile of glioma patients relative to differences in their tumour characteristics, and also whether any observed differences were representative of synchronously obtained glioma samples and TCGA glioma derived RNA.

Method

Blood samples were collected from twenty-nine patients prior to tumour resection. Plasma-ccfmRNA and glioma derived RNA were extracted and profiled.

Results

BCL2L1, CXCL5, GZMB, HLA-A, HLA-C, IRF1, MYD88, TGFB1, TLR2, and TP53 genes were significantly over-expressed in glioma (high-grade-glioma-HGG and low-grade-glioma-LGG) patients (p < 0.05, versus control). BCL2L1, GZMB and HLA-A genes were significantly over-expressed in HGG patients (p < 0.05, versus LGG patients). There was positive correlation between the magnitude of fold change of differentially expressed genes in plasma and glioma derived RNA (Spearman r = 0.6344, n = 14, p = 0.017), and with the mean FPKM of TCGA glioma derived RNA samples (Spearman r = 0.4614, n = 19, p = 0.047). There was positive correlation between glioma radiographic tumour burden and the magnitude of fold change of CSF3 gene (r = 0.9813, n = 20, p < 0.001).

Conclusions

We identified significant differential expression of genes involved in cancer inflammation and immunity among patients with different glioma grades, and we identified positive correlation between the plasma transcriptomic profile and tumour samples, and with TCGA glioma derived RNA.
1692 No Longer Unknown: A Systematic Review & Meta-Analysis of The Effectiveness of Trans-Oral Surgical Techniques in Identifying Head and Neck Primary Cancer in Carcinoma Unknown Primary
Authors: Gao C , Al-Lami A , Al-Zuhir N , Simo R , Arora A , Jeannon J P
Published: October 2021

Aim

The use of transoral robotic surgery (TORS), transoral laser microsurgery (TLM) and more recently reported transoral endoscopic electrocautery (TOEC) in the identification of the primary cancer in CUP patients has gained popularity. This systematic review aims to assess the effectiveness of TORS, TLM and TOEC.

Method

A systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting methodology was carried out to assess the effectiveness of the three trans-oral surgical techniques. EMBASE, MEDLINE and CINAHL databases were searched from inception to September 2020. Primary outcome measure was detection rates of primary cancer of the different techniques. Secondary outcome measures were complications and length of hospital stay.

Results

289 studies were identified of which 30 met the inclusion criteria (28 case series and 2 case reports). The overall combined primary identification rate was 72.3% (567 /777 patients). The primary identification rates were 49.7% and 34.2% in lingual (n = 273) and palatine tonsillectomy (n = 118) respectively. The primary cancer identification rates by surgical techniques are: TORS was 60% (CI 0.49, 0.70), TLM was 80% (CI 0.58, 1.01), TOEC was 41% (CI 0.05, 0.76). The commonest complication was haemorrhage (5.3%).

Conclusions

This is the largest systematic review in the subject and incorporates the more recently published surgical technique of TOEC. Lingual tonsillectomy is an effective procedure in CUP work up. Further larger, multi-centre, prospective studies of PET CT negative CUP patients is needed to draw conclusive results
715 The Importance of Social Media to The Academic Surgical Literature: Relationship Between Twitter Activity and Readership Metrics
Authors: Mobarak S , Stott M , Lee W J , Davé M , Tarazi M , Macutkiewicz C
Published: October 2021

Aim

Social media (SoMe) has an increasing role within professional surgical practice, including the publishing and engagement of academic literature. This study aims to analyse the relationship between social media use and traditional and alternative metrics amongst academic surgical journals.

Method

Journals were identified through the InCites Journal Citation Reports 2019, and their impact factor (IF), h-index and CiteScore were noted. Social media platforms were examined, and Twitter activity interrogated between 1st January- 31st December 2019. Healthcare Social Graph (HSG) score and an aggregated Altmetric score were also calculated for each journal. Statistical analysis was carried out to look at the correlation between traditional metrics, Twitter activity and altmetrics.

Results

Journals with higher IF were more likely to use a greater number of SoMe platforms (R2=0.648; p < 0.0001). Journals with dedicated Twitter profiles had a higher IF than journals without (median, 2.96 vs 1.88; MWU=390; p < 0.001) however over a one-year period (2018-2019) having a twitter presence did not alter IF (MWU=744.5; p = 0.885). Increased Twitter activity was positively correlated with IF. Longitudinal analysis over six years suggested cumulative tweets correlated with an increased IF (R2=0.324, p = 0.004). Novel alternative measures including HSG score (R2=0.472, p = 0.005) and Altmetric score (R2=0.779, p = 0.001) positively correlated with IF.

Conclusions

Higher IF is associated with SoMe presence and activity, particularly on Twitter, with long term activity being of particular importance. Modern alternative metrics correlate with IF. This relationship is complex and future studies should look to understand this further.
984 Changing the Management of Epistaxis in the Covid-19 Era
Authors: Kerr B , Dalton J , Stewart R , Stewart R , McGahey D
Published: October 2021

Aim

Epistaxis in the Covid pandemic is a concerning problem facing otolaryngologists due to high droplet concentration and increased virulence in nasal secretions. Furthermore, safe ambulation of patients reduces Covid exposure and preserves essential resources. This study assessed the implementation of ENT UK recommended altered epistaxis management during the Covid pandemic.

Method

Patients presenting to a medium-sized community hospital with unrelenting epistaxis had a rapid rhino (RR) inserted. Able patients were ambulated and given an appointment for RR removal. Previously all patients were admitted. A comparative retrospective analysis of patients referred with epistaxis was conducted using electronic care records from March – August 2019 versus the same period in 2020. Follow-up phone-call was also employed. Admissions, bed days, RR complications and patient satisfaction was assessed. Data was analysed student t-tests.

Results

A significant reduction in admissions (n = 91; P < 0.001) and bed days (n = 104; P < 0.001) was observed. Only 2 out of the 68 patients ambulated required medical assistance prior to their scheduled appointment (3%; P < 0.001). The majority of patients were satisfied (91%) and reported no bleeding (94%). No RR dislodgement occurred (0%) and most patients were pleased to avoid admission (92%). 70% of patients reported severe pain following RR insertion.

Conclusions

Ambulation of patients presenting to ED with unrelenting epistaxis managed with RR insertion is a safe alternative to previous practice with few complications. Furthermore, patients are largely satisfied although reported severe pain post RR insertion needs addressed. Finally, this altered management reduces contact and preserves resources as our hospitals face overwhelming pressures.
437 Impact of COVID-19 on West of Scotland Colorectal Cancer Services
Authors: Welsh S , Al-Ani A
Published: October 2021

Aim

The coronavirus disease 19 (COVID-19) pandemic has driven unprecedented restriction of the National Health Service to accommodate additional pressures. Our aim was to analyse the impact of COVID-19 on the largest colorectal cancer (CRC) services in NHS Greater Glasgow & Clyde.

Method

Audit data collected from multidisciplinary team meetings for South Glasgow CRC service were accessed. We compared April-June 2020 (‘Lockdown group’) to corresponding months in 2019 (‘Control group’). Statistical analysis by unpaired T-test, Pearson’s χ2 test with post hoc analysis using adjusted Z scores and Bonferroni correction as appropriate.

Results

There was a 39.5% reduction in CRC diagnoses during lockdown (n = 49) compared to control (n = 81). There was a 34.1% reduction in CRC operations during lockdown (n = 27) compared to control (n = 52). The proportion of patients managed operatively did not differ between groups (p = 0.140). There was no difference in the number of days from diagnosis to first treatment between Lockdown and Control groups (Mean(SD): 40.1±35.3 and 43.2±42.9, p = 0.257). Primary care physicians were the main referral source for both lockdown (52%) and control groups (46%). The cessation of bowel screening programme saw no referrals in lockdown whereas it accounted for 21% of referrals in control group, p < 0.001).

Conclusions

We experienced dramatic reductions in CRC diagnoses during lockdown that was not only accounted for by the cessation of bowel screening. The diagnostic delay in the 39.5% ‘missed’ CRC patients may result in patient morbidity; a severe repercussion of COVID-19. The resurgence of COVID-19 cases poses a real threat to cancer services.
6 The Value of Ultrasound in Diagnosing Acute Appendicitis
Authors: Ugwu G
Published: October 2021

Aim

The diagnosis of acute appendicitis relies on a thorough history and examination and can often be challenging. Ultrasound is widely considered to be the most appropriate first line investigation; however non-diagnostic ultrasounds are not uncommon and do lead to delays in diagnosis and/or definitive treatment by creating a need for further clinical assessment. The purpose of this study was to determine the sensitivity and specificity of ultrasound diagnosis of appendicitis in patient treated at Doncaster Royal Infirmary, and to determine the local negative appendicectomy rate.

Method

This was a retrospective analysis of 99 patients undergoing appendicectomy, with a prior ultrasound abdomen within one week of the procedure being undertaken. Data was collected from review of patient's hospital medical records (discharge summaries, clinic letters, PACs).

Results

99 patient aged 8-76 years were studied. Male to female ratios was 3:1. The sensitivity and specificity of ultrasound was 16% (95% CI - 7% to 29%) and 96% (95% CI - 86% to 99%) respectively with PPV of 80% and NPV of 52%. The accuracy of ultrasound diagnosis was found to be 55% (95% CI 44% to 65%). The negative appendicectomy rate was 48%.

Conclusions

From our study, ultrasound cannot reliably identify nor exclude appendicitis. Less than 16% of patients who had proven appendicitis (positive histology) had scans that indicated. Almost 50% of the normal/indeterminate scans were false negatives. Furthermore, 20% of positive ultrasound reports were false positives. A collaborative quality improvement project with the imaging department is planned to address these findings.