bluuebunny/crossref_metadata_2025 huggingface dataset:
A plexus‐convolutional neural network framework for fast remote sensing image super‐resolution in wavelet domain
Authors: Deeba Farah , Zhou Yuanchun , Dharejo Fayaz Ali , Khan Muhammad Ashfaq , Das Bhagwan , Wang Xuezhi , Du Yi
Published: February 2021

Satellite image processing has been widely used in recent years in a number of applications such as land classification, Identification transfer, resource exploration, super‐resolution image, etc. Due to the orbital location, revision time, quick view angle limitations, and weather impact, the satellite images are challenging to manage. There are many types of resolution, such as spatial, spectral, and temporal. Still, in our case, we concentrated on spatial image resolution to super resolve the images from low‐resolution images. For remote sensing image super‐resolution fast wavelet‐based super‐resolution (FWSR), we propose a novel, fast wavelet‐based plexus framework that performs super‐resolution convolutional neural network (SRCNN)‐like extraction of features based on three hidden layers. First, wavelet sub‐band images are combined into a pre‐defined full‐scale data training factor, including approximation and interchangeable stand‐alone units (frequency sub‐bands). Second, to speed up image recovery, mapping the sub‐band image of the wavelet is then measured using its approximate image. Third, the added sub‐pixel layer at the end of the network model is intended to reproduce image quality using a plexus framework. The approximation sub‐band images obtained after discrete wavelet transform wavelet decomposition are used as input rather than the original image because of their high‐frequency data and preserved characteristics. Five current super‐resolution neural network approaches are compared with the proposed technique and tested on three pubic satellite image datasets and two benchmark datasets. The experimental findings are well compared qualitatively and quantitatively.
Application of IoT‐Fog based real‐time monitoring system for open‐cast mines—A survey
Authors: Yadav Devendra Kumar , Mishra Pragyan , Jayanthu Singam , Das Santos Kumar , Sharma Sanjay Kumar
Published: February 2021

Fog computing (FC) archetypes is in focus recently for its potential to utilise resources optimally by the Internet of Things (IoT) network bearing ample end‐devices. This enhances the quality of service (QoS) to the proximity of end‐users as latency‐free processing is obtained in cloud‐IoT‐based environs. Mining industry will encounter a level‐up due to these technological advancements like fog‐IoT‐based systems. Monitoring mining activities such as blasting, slope monitoring, and miner tracking are time‐sensitive. Hence, instant response is demand of extreme mine environment so that life and property are not compromised. New opportunities emerge in mining since the FC approach addresses these demands depending on the demand of the situation/user. The parameters of integrating the state‐of‐art of fog, IoT, and cloud architectures are provided, and a Fog‐IoT mines monitoring (FIoTMM) system for real‐time monitoring of open‐cast mines is proposed. This work also envisions the applications and future trends of FC concerning IoT and cloud. It emphasises how key features of fog help the system in achieving lower network influx, reduced latency, resource utilisation, and immediate data computation and storage because these services take place closer to point of data generation. This data can be immediately visualised/accessed and used to generate early warning in the mines.
Size of particles ejected from an artificial impact crater on asteroid 162173 Ryugu
Authors: Wada K. , Ishibashi K. , Kimura H. , Arakawa M. , Sawada H. , Ogawa K. , Shirai K. , Honda R. , Iijima Y. , Kadono T. , Sakatani N. , Mimasu Y. , Toda T. , Shimaki Y. , Nakazawa S. , Hayakawa H. , Saiki T. , Takagi Y. , Imamura H. , Okamoto C. , Hayakawa M. , Hirata N. , Yano H.
Published: February 2021

A projectile accelerated by the Hayabusa2 Small Carry-on Impactor successfully produced an artificial impact crater with a final apparent diameter of 14.5 ± 0.8 m on the surface of the near-Earth asteroid 162173 Ryugu on April 5, 2019. At the time of cratering, Deployable Camera 3 took clear time-lapse images of the ejecta curtain, an assemblage of ejected particles forming a curtain-like structure emerging from the crater. Focusing on the optical depth of the ejecta curtain and comparing it with a theoretical model, we infer the size of the ejecta particles. As a result, the typical size of the ejecta particles is estimated to be several centimeters to decimeters, although it slightly depends on the assumed size distribution. Since the ejecta particles are expected to come from a depth down to ~1 m, our result suggests that the subsurface layer of Ryugu is composed of relatively small particles compared to the uppermost layer on which we observe many meter-sized boulders. Our result also suggests a deficit of particles of less than ~1 mm in the subsurface layer. These findings will play a key role in revealing the formation and surface evolution process of Ryugu and other small Solar System bodies.
Evidence of theGaia–VLBI position differences being related to radio source structure
Authors: Xu Ming H. , Lunz Susanne , Anderson James M. , Savolainen Tuomas , Zubko Nataliya , Schuh Harald
Published: February 2021

Context.We report the relationship between theGaia–VLBI position differences and the magnitudes of source structure effects in VLBI observations.

Aims.Because theGaia–VLBI position differences are statistically significant for a considerable number of common sources, we discuss and attempt to explain these position differences based on VLBI observations and available source images at centimeter wavelengths.

Methods.Based on the derived closure amplitude root mean square (CARMS), which quantifies the magnitudes of source structure effects in the VLBI observations used for building the third realization of the International Celestial Reference Frame, the arc lengths and normalized arc lengths of the position differences are examined in detail. The radio-jet directions and the directions of theGaia–VLBI position differences are investigated for a small sample of sources.

Results.Both the arc lengths and normalized arc lengths of theGaiaand VLBI positions are found to increase with the CARMS values. The majority of the sources with statistically significant position differences are associated with the sources having extended structure. Radio source structure is the one of the major factors of these position differences, and it can be the dominant factor for a number of sources. The vectors of theGaiaand VLBI position differences are parallel to the radio-jet directions, which is confirmed via stronger evidence.
Rubidium abundances in solar metallicity stars
Authors: Abia C. , de Laverny P. , Korotin S. , Asensio Ramos A. , Recio-Blanco A. , Prantzos N.
Published: February 2021

Context. Rubidium is one of the few elements produced by the neutron capture s- and r-processes in almost equal proportions. Recently, a Rb deficiency ([Rb/Fe] < 0.0), amounting to a factor of about two with respect to the Sun, has been found in M dwarfs of near-solar metallicity. This stands in contrast to the close-to-solar [Sr, Zr/Fe] ratios derived in the same stars. This deficiency is difficult to understand from the point of view of observations and of nucleosynthesis.

Aims. To test the reliability of this Rb deficiency, we study the Rb and Zr abundances in a sample of KM-type giant stars across a similar metallicity range, extracted from the AMBRE Project.

Methods. We used high-resolution and high signal-to-noise spectra to derive Rb and Zr abundances in a sample of 54 bright giant stars with metallicities in the range of −0.6 ≲ [Fe/H] ≲ +0.4 dex, via spectral synthesis in both local and non-local thermodynamic equilibrium (LTE and NLTE, respectively). We also studied the impact of the Zeeman broadening in the profile of the Rb I at λ7800 Å line.

Results. The LTE analysis also results in a Rb deficiency in giant stars, however, it is considerably lower than that obtained in M dwarfs. However, once NLTE corrections are performed, the [Rb/Fe] ratios are very close to solar (average −0.01 ± 0.09 dex) in the full metallicity range studied here. This stands in contrast to the value found for M dwarfs. The [Zr/Fe] ratios derived are in excellent agreement with those obtained in previous studies in FGK dwarf stars with a similar metallicity. We investigate the effect of gravitational settling and magnetic activity as possible causes of the Rb deficiency found in M dwarfs. Although the former phenomenon has a negligible impact on the surface Rb abundance, the presence of an average magnetic field with an intensity that is typical of that observed in M dwarfs may result in systematic Rb abundance underestimations if the Zeeman broadening is not considered in the spectral synthesis. This may explain the Rb deficiency in M dwarfs, but not fully. On the other hand, the new [Rb/Fe] and [Rb/Zr] versus [Fe/H] relationships can be explained when the Rb production by rotating massive stars and low-to-intermediate mass stars (these latter also producing Zr) are considered, without the need to deviate from the standard s-process nucleosynthesis in asymptotic giant branch stars, as suggested previously.
Alternative Übertragungswege von Arboviren
Authors: Kohsar Matin , Kreuels Benno
Published: February 2021

Das Denguevirus (DENV) ist ein humanpathogenes Virus aus der Familie der Flaviviren, welches schwere Verlaufsformen verursachen kann. Eine kausale Therapie existiert nicht, seit 2015 ist ein Impfstoff verfügbar, der allerdings ausschließlich für die Impfung der Bevölkerung von hochendemischen Gebieten empfohlen wird 1. Die Übertragung erfolgt, wie bei dem verwandten Zikavirus (ZIKV), primär über Stiche von infizierten Aedes-Mücken. Nachdem bei ZIKV die sexuelle Transmission als relevante Übertragungsroute nachgewiesen wurde, stellt sich die Frage, ob auch DENV sexuell übertragen wird.
Dysphagie bei Multipler Sklerose – ein unterschätztes Symptom?
Authors: Eckardt Carolin , Vay Sabine Ulrike , Warnke Clemens , Flossdorf Pia , Weinert Melanie
Published: February 2021

Hintergrund In Deutschland sind schätzungsweise 240.000 Menschen an Multipler Sklerose (MS) erkrankt. Neben sensiblen, motorischen, vegetativen und neuropsychologischen Funktionsstörungen ist die Dysphagie ein sicherlich hochrelevantes, stark beeinträchtigendes und zugleich bislang nicht gut untersuchtes Symptom der Erkrankung.

Ziel der Arbeit Dieser Artikel soll eine Übersicht über die aktuelle Studienlage zur Dysphagie bei MS geben und es dem Leser ermöglichen, die Wahrnehmung für das Symptom Schluckstörung zu schärfen. Techniken zur weiterführenden Diagnostik und Therapie werden vorgestellt mit dem langfristigen Ziel, betroffenen Patienten mit MS zukünftig verbesserte Hilfe zu bieten und ihre Lebensqualität zu verbessern.

Methode Zur Entstehung, Manifestation, Diagnostik- und Therapiemöglichkeiten bei MS-bedingter Dysphagie wurde eine strukturierte Literaturrecherche zur aktuellen Studienlage in pubmed durchgeführt. Aufgrund fehlender Klasse-1-Evidenz aus prospektiven Studien, insbesondere zur Diagnostik und zu den Therapiemöglichkeiten, wurden auch Studien mit kleineren Fallzahlen oder Pilotprojekte mit berücksichtigt.

Ergebnisse und Diskussion In bildgebenden Methoden, wie der Fiberoptischen Endoskopischen Evaluation des Schluckens und der Videofluroskopie, lassen sich Schluckstörungen objektivieren. Je nach gewählter Methode zur Erfassung der Schluckstörung wird die Häufigkeit der Dysphagie bei MS-Erkrankten sehr unterschiedlich angegeben (von 38 % bis 81 %). Es ist jedoch davon auszugehen, dass die Dysphagie als bewusstes Symptom sowohl vonseiten der betroffenen Personen mit Multipler Sklerose als auch ihren Behandlern stark unterschätzt wird. Spezifische Behandlungen werden laut aktueller Daten aus dem deutschen MS-Register nur bei 30 % der betroffenen Patienten durchgeführt.
Dehnen versus Krafttraining: Effekte auf die Beweglichkeit
Authors: Scheinost David
Published: February 2021

Möchten Patienten oder Sportler ihre Beweglichkeit verbessern, liegt das Dehnen als Maßnahme nahe. Ein Krafttraining erhöht aber genauso, wenn nicht sogar stärker, das Bewegungsausmaß und bringt dazu noch andere positive gesundheitliche Effekte mit sich. Vor allem das exzentrische Training mobilisiert das Muskel- und Bindegewebe.
Muskuloskelettale Therapie im Praxisalltag bei Patienten mit Gonarthrose
Authors: Ebling Christopher
Published: February 2021

Gonarthrose gehört zu den häufigsten Krankheitsbildern in Deutschland und verursacht Invalidität, Arbeitsunfähigkeit und Einbußen in der Lebensqualität. Dies führt zu Herausforderungen für konservative Therapien, insbesondere die Manuelle Therapie, die trotz wissenschaftlicher Empfehlungen insuffizient verordnet wird. Ziel der Arbeit war, hemmende und fördernde Faktoren im Praxisalltag von Ärzten, Physiotherapeuten und Patienten bei der Wahl von Manueller Therapie bei Gonarthrose herauszufinden. In der qualitativen Studie wurden 23 Ärzte, Physiotherapeuten und Patienten in halbstrukturierten Interviews befragt. Die Transkriptionen wurden mittels zusammenfassender Inhaltsanalyse ausgewertet. Daraus wurden induktiv Kategorien gebildet.

Vier Kategorien wurden identifiziert, die hemmende und fördernde Aspekte bei der Wahl von Manueller Therapie bei Gonarthrose lieferten: „Bedingungen im Gesundheitssystem“, „Erfahrungen mit der Therapiemethode Manuelle Therapie“, „Die Rolle der Patienten“ und „Zusammenarbeit“. Diese geben Aufschlüsse bezüglich der Entscheidungen der Gesundheitsdienstleister und Patienten bei der Wahl von Manueller Therapie in der konservativen Therapie von Gonarthrose.
Axiale Spondyloarthritis erkennen
Authors: Vielitz Arne
Published: February 2021

Magrey MN, Danve AS, Ermann J et al. Recognizing Axial Spondyloarthritis: A Guide for Primary Care. Mayo Clin Proc 2020; 95: 2499–2508. doi:10.1016/j.mayocp.2020.02.007
Chemosaturation with Percutaneous Hepatic Perfusion: Outcome and Safety in Patients with Metastasized Uveal Melanoma
Authors: Dewald Cornelia Lieselotte Angelika , Hinrichs Jan B. , Becker Lena Sophie , Maschke Sabine , Meine Timo C. , Saborowski Anna , Schönfeld Leon Jonas , Vogel Arndt , Kirstein Martha M. , Wacker Frank K.
Published: February 2021

Purpose Chemosaturation percutaneous hepatic perfusion (CS-PHP) allows selective intrahepatic delivery of high dose cytotoxic melphalan in patients with curatively untreatable liver tumors while limiting systemic toxicity through hemofiltration of the hepatic venous blood. Aim of this study was to investigate the response to therapy, survival and safety of the CS-PHP procedure in patients with liver-dominant metastatic uveal melanoma (UM).

Materials and Methods Overall response rate (ORR) and disease control rate (DCR) were assessed according to Response Evaluation Criteria In Solid Tumors (RECIST1.1). Median overall survival (mOS), median progression-free survival (mPFS) and hepatic progression-free survival (mhPFS) were analyzed using Kaplan-Meier estimation. Adverse events were evaluated with Common Terminology Criteria for Adverse Events (CTCAE) v5.

Results Overall, 30 patients were treated with 70 CS-PHP in a salvage setting from October 2014 to January 2019. In total, ORR and DCR were 42.3 % and 80.8 %, respectively. Overall, mOS was 12 (95 % confidence interval (CI) 7–15) months, and both, mPFS and mhPFS were 6 months, respectively (95 % CI 4–10; 95 % CI 4–13). Adverse events (AE) most frequently included significant but transient hematologic toxicities (87 % of grade 3/4 thrombocytopenia), less frequent AEs were hepatic injury extending to liver failure (3 %), cardiovascular events including one case of ischemic stroke (3 %).

Conclusion Salvage treatment with CS-PHP is effective in selected patients with UM. The interventional procedure is safe. Serious hepatic and cardiovascular events, although rare, require careful patient selection and should be closely monitored.

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Total Flavonoids of Bidens pilosa Ameliorates Bone Destruction in Collagen-Induced Arthritis
Authors: Hong Mengqin , Fan Xingyu , Liang Shengxiang , Xiang Wang , Chen Liting , Yang Yuzhong , Deng Yueyi , Yang Min
Published: February 2021

Rheumatoid arthritis is a chronic autoimmune disease characterized by the infiltration of synovial inflammatory cells and progressive joint destruction. Total flavonoids of Bidens pilosa have been used against inflammation in rheumatoid arthritis, but its role in bone destruction remains to be explored. The aim of this paper was to study whether total flavonoids of B. pilosa relieve the severity of collagen-induced arthritis in rats, particularly whether it regulates the production of proinflammatory cytokines and the receptor activator of nuclear factor-κB/receptor activator of nuclear factor-κB ligand/osteoprotegerin signaling pathway. In this research, a collagen-induced disease model was induced in adult rats by subcutaneous injection of collagen II. Total flavonoids of B. pilosa at different doses (40, 80, and 160 mg/kg/d) were administered intragastrically, while methotrexate (1 mg/kg/w) was injected intraperitoneally as a positive control. Paw swelling, arthritis score, and body weight were assessed and evaluated. The severity of joint damage was determined using X-ray and confirmed by histopathology. The expression levels of receptor activator of nuclear factor-κB ligand, osteoprotegerin, IL-1β, IL-17, and TNF in the serum and tissue were assayed using ELISA and immunohistochemistry. We found that total flavonoids of B. pilosa attenuated collagen-induced arthritis at the macroscopic level, and total flavonoids of B. pilosa-treated rats showed reduced paw swelling, arthritis scores, and X-ray appearance of collagen-induced arthritis in addition to improved histopathological results. These findings were consistent with reduced serum and tissue receptor activator of nuclear factor-κB ligand, TNF, IL-1β, and IL-17 levels but increased osteoprotegerin levels. Our data suggest that total flavonoids of B. pilosa attenuate collagen-induced arthritis by suppressing the receptor activator of nuclear factor-κB ligand/receptor activator of nuclear factor-κB/osteoprotegerin pathway and the subsequent production of proinflammatory cytokines. In addition, total flavonoids of B. pilosa may be a promising therapeutic candidate for the management of rheumatoid arthritis.
Inferior Vena Cava Filter Retrieval Trends: A Single-Center Experience
Authors: Ionescu Filip , Anusim Nwabundo , Ma Eva , Qu Lihua , Blankenship LeAnn M. , Stender Michael , Jaiyesimi Ishmael
Published: February 2021

Recognition of the adverse events of inferior vena cava filters (VCFs) has prompted the Food and Drug Administration (FDA) to issue safety warnings (2010 and 2014), advocating for removal, once the risk of pulmonary embolism has abated. Despite an initial increase in retrieval rates, these remain low (25–30% at 1 year in 2014). We retrospectively investigated retrieval trends in adults with VCFs placed between 2015 and 2018 at a single institution. The rate of retrievable VCF removal accounting for the competing risk of death was the main outcome. There were 494 VCFs placed (305 retrievable). The cumulative incidence of retrieval remained low (21% at 1 year), even after the second FDA warning (2014). Patients who resumed anticoagulation (AC) at any time were more likely to have retrieval (hazard ratio [HR] = 3.6, p < 0.01) and had higher retrieval rates at every time point (31.4 vs. 7.6% at 1 year). Advanced age (HR = 0.98 per year, p = 0.004), stroke (HR = 0.28, p = 0.028), and active malignancy (HR = 0.42, p = 0.006) predicted nonretrieval. Device-related complications were infrequent (<1%) but thrombotic complications occurred early and were more common for nonretrieved VCFs (17 vs. 12%, p = 0.29). Revision of guidelines to recommend active surveillance for the ability to tolerate AC in the immediate postimplantation period may improve retrieval rates.
Pediatric Reversible Cerebral Vasoconstriction Syndrome: Two Unique Cases with a Review of all Reported Children
Authors: Desai Neelu , Badheka Rahul , Shah Nitin , Udani Vrajesh
Published: February 2021

Reversible cerebral vasoconstriction syndrome (RCVS) has been well described in adults, but pediatric cases are yet under recognized. We described two children with RCVS and review similar already published pediatric cases. The first patient was a 10-year-old girl who presented with severe headaches and seizures 3 days after blood transfusion. Brain magnetic resonance imaging (MRI) showed changes compatible with posterior reversible encephalopathy syndrome and subarachnoid hemorrhage. Magnetic resonance angiogram showed diffuse vasoconstriction of multiple cerebral arteries. The second patient was a 9-year-old male child who presented with severe thunderclap headaches. Brain MRI showed isolated intraventricular hemorrhage. Computed tomography/MR angiogram and digital subtraction angiogram were normal. A week later, he developed focal neurological deficits. Repeated MR angiogram showed diffuse vasospasm of multiple intracranial arteries. Both children recovered completely. A clinico-radiological review of previously reported childhood RCVS is provided.
Inconsistency of Karyotyping and Array Comparative Genomic Hybridization (aCGH) in a Mosaic Turner Syndrome Case
Authors: Tulay Pinar , Ergoren Mahmut Cerkez , Alkaya Ahmet , Yayci Eyup , Sag Sebnem Ozemri , Temel Sehime Gulsum
Published: February 2021

Purpose Turner syndrome is a sex chromosomal aberration where majority of the patients have 45,X karyotype, while several patients are mosaic involving 45,X/46,XX; 46,X,i(Xq); and other variants. Cytogenetic analysis, karyotyping, is considered to be the “gold standard” to detect numerical and structural chromosomal abnormalities. In the recent years, alternative approaches, such as array comparative genomic hybridization (aCGH), have been widely used in genetic analysis to detect numerical abnormalities as well as unbalanced structural rearrangements. In this study, we report the use of karyotyping as well as aCGH in detecting a possible Turner syndrome variant.

Methods An apparent 16-year-old female was clinically diagnosed as Turner syndrome with premature ovarian failure and short stature. The genetic diagnosis was performed for the patient and the parents by karyotyping analysis. aCGH was also performed for the patient.

Main Findings Cytogenetic analysis of the patient was performed showing variant Turner syndrome (46,X,i(X)(q10)[26]/46,X,del(X)(q11.2)[11]/45,X[8]/46,XX[5]). The patient's aCGH result revealed that she has a deletion of 57,252kb of Xp22.33-p11.21 region; arr[GRCh37] Xp22.33-p11.21 (310,932–57,563–078)X1. Both aCGH and fluorescence in situ hybridization (FISH) results suggested that short stature Homeobox-containing (SHOX) gene, which is located on Xp22.33, was deleted, though FISH result indicated that this was in a mosaic pattern.

Conclusion In the recent years, aCGH has become the preferred method in detecting numerical abnormalities and unbalanced chromosomal rearrangements. However, its use is hindered by its failure of detecting mosaicism, especially low-level partial mosaicism. Therefore, although the resolution of the aCGH is higher, the cytogenetic investigation is still the first in line to detect mosaicism.
The Impact of Implementing a “Pain, Agitation, and Delirium Bundle” in a Pediatric Intensive Care Unit: Improved Delirium Diagnosis
Authors: Cloedt Lise D. , Benbouzid Kenza , Lavoie Annie , Metras Marie-Élaine , Lavoie Marie-Christine , Harakat Samira , Harrington Karen , Ducharme-Crevier Laurence
Published: February 2021

Delirium is associated with significant negative outcomes, yet it remains underdiagnosed in children. We describe the impact of implementing a pain, agitation, and delirium (PAD) bundle on the rate of delirium detection in a pediatric intensive care unit (PICU). This represents a single-center, pre-/post-intervention retrospective and prospective cohort study. The study was conducted at a PICU in a quaternary university-affiliated pediatric hospital. All patients consecutively admitted to the PICU in October and November 2017 and 2018. Purpose of the study was describe the impact of the implementation of a PAD bundle. The rate of delirium detection and the utilization of sedative and analgesics in the pre- and post-implementation phases were measured. A total of 176 and 138 patients were admitted during the pre- and post-implementation phases, respectively. Of them, 7 (4%) and 44 (31.9%) were diagnosed with delirium (p < 0.001). Delirium was diagnosed in the first 48 hours of PICU admission and lasted for a median of 2 days (interquartile range [IQR]: 2–4). Delirium diagnosis was higher in patients receiving invasive ventilation (p < 0.001). Compliance with the PAD bundle scoring was 79% for the delirium scale. Score results were discussed during medical rounds for 68% of the patients in the post-implementation period. The number of patients who received opioids and benzodiazepines and the cumulative doses were not statistically different between the two cohorts. More patients received dexmedetomidine and the cumulative daily dose was higher in the post-implementation period (p < 0.001). The implementation of a PAD bundle in a PICU was associated with an increased recognition of delirium diagnosis. Further studies are needed to evaluate the impact of this increased diagnostic rate on short- and long-term outcomes.
Purely Intraventricular Desmoplastic Infantile Astrocytoma
Authors: Nicoletti Giovanni Federico , Umana Giuseppe Emmanuele , Riolo Carmelo , Magro Gaetano , Bartoloni Giovanni , Scalia Gianluca
Published: February 2021

Desmoplastic infantile astrocytomas (DIAs) are rare pediatric tumors characterized by superficial brain cortex involvement, along with the meninges of the supratentorial compartment, and are classified as grade I neoplasms according to the 2016 World Health Organization. A 5-year-old girl child patient was admitted to our unit with abnormal decorticate posturing, bilateral mydriasis with weak pupillary light reflex, and brisk lower limbs reflexes. Her medical history was unremarkable. Magnetic resonance imaging of the brain revealed a massive lesion with bilateral intraventricular growth mainly prevailing on the left and involving the ipsilateral foramen of Monro. After external ventricular drainage positioning, Dandy's transfrontal transcortical approach to the left lateral ventricle, a meticulous ependymal microsurgical dissection of the lesion was performed, resulting in an excision of the cystic component of the left lateral ventricle. A gross total removal of the lesion was performed with an en bloc resection of the deeper cystic part. Thirty days after surgery, the patient presented with fluent speech, conserved axial, and extremity sensorimotor functions, except a mild central facial paresis which progressively improved. To the best of our knowledge, this is the first case of DIA characterized by purely intraventricular growth. Tumor recurrence, although considered rare, represents an unpredictable event. Therefore, an adequate follow-up must be reserved for each patient.
Characteristic analysis of electromagnetic acoustic transducers for helical shear horizontal wave based on magnetostrictive effect
Authors: Huang Songling , Wang Zhe , Wang Shen , Wang Qing , Zhao Wei
Published: February 2021

The electromagnetic ultrasound detection technology provides an efficient method to inspect the structural health status. For the pipeline structure, the guided ultrasonic wave propagating along the axial direction has been the focus of the current research. However, the helical wave owns the advantage of obtaining the defect information in extra angles and has not been explored sufficiently. In this work, a transducer with a sector configuration is designed for generating helical shear horizontal waves in a pipeline. The magnetostrictive effect is analyzed, and the model is built in the finite element simulation software of COMSOL Multiphysics. The electromagnetic field and displacement distribution are studied. To evaluate the performance of the transducer, the half divergence angle is defined to measure the acoustic beam and evaluate the capacity in generating helical waves. Corresponding experiments are also implemented to analyze the influencing factors in the structural design of the transducer. The results indicate that the pulse cycle affects the half divergence angle slightly. The compromise should be considered when designing the central angle of the transducer because it influences the signal amplitude and further imaging resolution in a contradictory way.
High quantum efficiency GaAs photocathodes activated with Cs, O2, and Te
Authors: Biswas Jyoti , Wang Erdong , Gaowei Mengjia , Liu Wei , Rahman Omer , Sadowski Jerzy T.
Published: February 2021

GaAs photocathodes are the primary choice for generating spin-polarized electron beam with high brightness, high polarization, and fast polarization reversal. However, it suffers from short lifetime due to the highly reactive nature of the emission surface, resulting in substantial operational difficulties. Activating GaAs with a more robust material, such as Cs2Te, shows comparable polarization to that of Cs–O activation and increases the lifetime due to the robustness of the Cs2Te layer. However, previously reported photocathodes based on Cs–Te activation on GaAs suffer from 10× lower quantum efficiency (QE) compared to that activated with conventional Cs–O activation. Herein, we report activation recipes for GaAs photocathodes using Cs, O2, and Te. For Cs–Te activation, the QE was 6.6% at 532 nm. For Cs–O–Te activation, the QE was 8.8% at 532 nm and 4.5% at 780 nm. The negative electron affinity of the activated GaAs was directly measured and confirmed by low energy electron microscopy. We also report the activation layer chemical states and stoichiometry using in situ micro-spot synchrotron radiation x-ray photoelectron spectroscopy.
Hydrogen negative ion density measurement by laser photodetachment and the effect of H recombination on the walls
Authors: Park Min , Na Byungkeun , Kwak Jong-Gu , Kim Tae-seong , Jung Bongki , Huh Sung-Ryul , Jeong Seung Ho
Published: February 2021

A laser photodetachment (LPD) was applied to measure the absolute hydrogen negative ion (H−) density in an RF negative ion source. The ion source has been developed to study a Cs-free ion source utilizing a magnetic filter by permanent magnets to enhance the volume production of H− in the extraction region. Prior to a beam extraction experiment, the laser photodetachment was applied as an initial performance evaluation. The absolute H− densities were obtained by LPD with the variation of the RF power. The H− density reached 1.8×109 cm−3 at an RF power of 5 kW. The comparison with the calculation of a particle balance model showed the discrepancy between the model and the LPD results. The LPD result showed the rapid increase in H− density with respect to the RF power compared to the model. By assuming the wall temperature increase and adjusting the recombination coefficient (γrec) of hydrogen (H) atoms on the walls, the discrepancy could be resolved. The recombination coefficient (γrec) plays an important role in determining the H− density in view of the fact that it can affect both the generation and the destruction processes of H−.
Research on micro-leverage in monolithic quartz resonant accelerometer
Authors: Li Cun , Han Chao , Zhao Yulong , Zhang Quanwei , Li Bo
Published: February 2021

In this study, the application of micro-leverage in the monolithically all-quartz resonant accelerometer is proposed. The magnification of the micro-leverage structure used for a large size double-ended tuning fork (DETF) was analyzed. The effect of DETF’s dimension both on its own force–frequency sensitivity and micro-leverage’s magnification was investigated. Through the study of the relationship between DETF’s force–frequency sensitivity and micro-leverage’s magnification, the effect of micro-leverage and the DETF system on the sensitivity of the accelerometer was obtained. The problem of big error in theoretical calculation of micro-leverage magnification was solved because the structural arrangement of the output beam was ignored in the derivation process. The correctness of the analysis was verified by theoretical calculation, simulation, and the experiment. The equivalent structures of tension (compression) stiffness and flexural stiffness of the micro-leverage output beam were obtained by analyzing and simplifying the composite structure of the link beam and DETF. By simplifying the mechanical model of micro-leverage, the amplification factor K of micro-leverage is deduced to be 23. Therefore, the theoretical sensitivity of the sensor is 15.6 Hz/g. The experimental results show that the sensitivity of the accelerometer with the micro-leverage is 16.1 Hz/g, which is close to the theoretical analysis results.
Energy harvester using piezoelectric nanogenerator and electrostatic generator
Authors: Erturun Ugur , Eisape Adebayo A. , Kang Sung Hoon , West James E.
Published: February 2021

This study demonstrates an energy harvester that combines a piezoelectric nanogenerator and an electret-based electrostatic generator. The device consists of an in-house fabricated nanocomposite (polydimethylsiloxane/barium titanate/carbon nanotube) as a piezoelectric layer and a monocharged Teflon fluorinated ethylene propylene as an electret electrostatic layer. The mechanical impedance of the structure can be altered easily by changing the nanocomposite monomer/cross-linker ratio and optimizing various mechanical energy sources. The energy harvester's performance was characterized by performing measurements with different frequencies (5–20 Hz) under applied dynamic loading. A total volumetric power density of ∼8.8 μW cm−3 and a total stored energy of ∼50.2 μJ min−1 were obtained. These findings indicate that this versatile, lightweight, and low-cost energy harvester can be employed as a power supply source for microelectronics in applications, such as wearables.
Experimental plasma maser as a broadband noise amplifier. II. Short pulse
Authors: Buleyko Alla B. , Ponomarev Anatoly V. , Loza Oleg T. , Ulyanov Denis K. , Sharypov Konstantin A. , Shunailov Sergey A. , Yalandin Michael I.
Published: February 2021

This paper presents an experimental plasma maser driven by a 2-ns long, high-current electron beam with a typical particles energy of 270 ± 10 keV, a pulsed power of 450 ± 30 MW, and a total energy of 0.85 ± 0.03 J. Tunable plasma characteristics define variations in the spectral maxima of excited high-power microwaves in the range from 3 to 25 GHz. The short beam current pulse has provided the device operation in the mode of a noise amplification with the energy efficiency of 26% ± 3%, mean microwave power over the beam current pulse of 117 ± 10 MW, and an instant (peak) power of up to 430 ± 30 MW.
The role of standing wave in the generation of hot electrons by femtosecond laser beams incident on dense ionized target
Authors: Babjak R. , Psikal J.
Published: February 2021

We demonstrate the differences in hot electron absorption mechanisms dominant in the interaction of a femtosecond laser pulse with intensities of 1018 W/cm2 and 1021 W/cm2 on a fully ionized target with a steep density profile and preplasma with moderate scale length (3 μm). We show that acceleration of each electron starts at the moment when the magnetic component of a standing electromagnetic wave changes its polarity in a regime without preplasma. In the presence of preplasma, the stochastic heating is the dominant absorption mechanism along with the longitudinal electric field. It is observed that wave's energy is absorbed only if the standing wave is already created at the position of electron during the interaction with the pulse with an intensity of 1018 W/cm2. In the case with 1021 W/cm2 intensity, the part of the electrons is pre-accelerated in front of the target before the reflection and following stochastic heating. The presence of preplasma results in electron temperatures close to or even exceeding ponderomotive scaling. At higher intensity, the re-injection of electrons previously repelled by incident wave's ponderomotive force into high-field regions is allowed if the standing wave is created.
Efficient scattering-free wavefront transformation with power flow conformal bianisotropic acoustic metasurfaces
Authors: Peng Xiuyuan , Li Junfei , Shen Chen , Cummer Steven A.
Published: February 2021

Bianisotropic metasurfaces have enabled highly efficient wavefront transformation. However, a passive and lossless bianisotropic metasurface must conserve local power at every point over the metasurface, hindering its application in handling complicated wavefields other than plane waves. In this paper, the power flow-conformal design methodology and bianisotropic unit cells are combined to comply with such a restriction. Our proposed approach provides a general recipe for arbitrary wavefront transformation with maximum power efficiency. As a demonstration, a transmission-type acoustic metasurface was designed to focus 3000 Hz plane wave airborne sound in the near field with theoretically unitary power efficiency. The metasurface was validated by both numerical simulation and experiment.
Mechanisms of low-frequency dielectric barrier discharge (DBD) plasma driven by unipolar pulses and bipolar pulses
Authors: Truong Hoa Thi , Uesugi Yoshihiko , Nguyen Xuan Bao
Published: February 2021

In this study, experimental results presenting the development of Dielectric Barrier Discharge (DBD) powered by bipolar and unipolar pulses are compared. The experimental results showed that discharge current peaks in the case of DBD driven by repetitive unipolar pulses were about three times lower than those in the case of DBD driven by bipolar pulses. It is well known that if DBD is driven by bipolar pulses, the effect of surface charge on dielectric layers from the preceding discharge helps to ignite consecutive discharges at the same locations where the previous discharges already struck. In contrast, in the case of DBD generated by using the low-frequency unipolar pulses, the consecutive DBDs just could be initiated after the system erases part of the prehistory effect of surface charge deposition on dielectric layers from the preceding discharge, and then the following discharge was ignited at erased or uncharged areas. It was critical that a part of the energy stored in the dielectric layer and discharge gap by the previous discharge needed to be released to develop the next discharge. The results of this study provided an outlook for estimating the effectiveness of the DBD plasma system used in specific applications such as DBD for flow actuators or surface treatment where the use of unipolar DBDs at low frequency may be necessary.
GaN bandgap bias caused by semi-core treatment in pseudopotentials analyzed by the diffusion Monte Carlo method
Authors: Nikaido Yutaka , Ichibha Tom , Nakano Kousuke , Hongo Kenta , Maezono Ryo
Published: February 2021

This study investigates how the prediction of the gallium nitride (GaN) bandgap is affected by treating semi-core d-electrons as either valence or core states in the pseudopotentials, which correspond to small-core and large-core approximations, respectively. To distinguish the effect of semi-core treatment from another bandgap problem recognized in density functional theory (DFT), that is, the underestimation related to the self-interaction problem, we perform diffusion Monte Carlo (DMC) evaluations under the fixed-node approximation and the optical gap scheme (where the evaluation uses N-electron many-body wavefunctions). A comparison to experimental measurements of bandgap energies indicates that DMC predictions are overestimated, whereas DFT simulations, which are used as a guiding function (DFT → DMC), are typically underestimated. This agrees with the trend reported in previous DMC studies on bandgap estimates. The large-core approximation results in a greater overestimation than the small-core treatment in both DFT and DMC. The bias in the overestimation is ∼30% for the DFT → DMC operation. Several possible causes of this bias are considered, such as pd-hybridization, core-polarization, and electronic screening effects. However, although these factors could qualitatively account for the overestimation caused by the large-core treatment, the estimated magnitude of the bias is too small to explain the evaluated difference between small-core and large-core approximations of the bandgap.
Comparison of enhanced second harmonic generation in pyramid-like in-plane MoS2 flakes to vertically aligned MoS2 flakes
Authors: Agrawal Abhay V. , Lemasters Robert , Li Chentao , Mojibpour Ali , Bharadwaj Palash , Harutyunyan Hayk , Kumar Mukesh
Published: February 2021

Here, we report the comparative study of enhanced second harmonic generation using defect engineering in pyramid-like MoS2 (P-MoS2) flakes to vertically aligned MoS2 (VA-MoS2) flakes. P-MoS2 and VA-MoS2 is synthesized via the modified chemical vapor deposition technique. The second harmonic generation measurements on P-MoS2 and VA-MoS2 are performed by sweeping the excitation wavelength from 1200 nm to 1310 nm in identical conditions. The P-MoS2 flakes show a high SHG signal. The high SHG signal in pyramid-like MoS2 is attributed to the broken inversion symmetry and high thickness of grown MoS2 flakes. VA-MoS2 flakes under the identical conditions show a 34% enhanced SHG signal in comparison to P-MoS2. The midgap states generated due to defects in the form of S vacancies in VA-MoS2 are responsible for this enhancement. These midgap states confine the photons and result in enhanced SHG properties. Our study will pave a new path to understand the role of 2D material morphology in fabricating versatile optical and photonics devices.
Large spin Hall angle enhanced by nitrogen incorporation in Pt films
Authors: Xu Zhan , Wong Grayson Dao Hwee , Tang Jiaxuan , Liu Er , Gan Weiliang , Xu Feng , Lew Wen Siang
Published: February 2021

We report on the enhancement of spin Hall angle from the CoFeB/Pt interface by introducing nitrogen into the Pt thin film. Spin-torque ferromagnetic resonance measurements on the effective spin Hall angle (θSH) reveal a non-monotonic variation as a function of the amount of nitrogen gas introduced, Q in the film deposition, which peaks at θSH = 0.16 when Q is 8%. Our analysis shows that the θSH enhancement is mainly attributed to the increase in spin-dependent scattering at the interface. The effective magnetic damping decreases with increasing Q due to the reduced spin–orbit coupling. The interfacial spin transparency is also observed to show improvement after the introduction of nitrogen. Moreover, the additional damping-like torque from the interface may also lead to the enhancement of the linewidth modulation.
Cherenkov radiation of the fast magnetoacoustic waves in the non-uniform magnetospheric plasma
Authors: Klimushkin Dmitri Yu. , Mager Pavel N.
Published: February 2021

The paper is concerned with the spatial structure of the fast magnetoacoustic mode generated by the super-Alfvénic source moving on the magnetopause in one-dimensionally inhomogeneous model of the magnetosphere. The moving source generates the Mach cone expanding with the local Alfvén speed. The Mach cone is reflected from the surface where the local Mach number equals one. This surface can be coined as the reflection surface. Then, the Mach cone expands outside and reflects from the magnetopause. Reflections from the reflection surface and the magnetopause lead to turning the Mach cone into the curved polyline.
A conservative and consistent scalar filtered mass density function method for supersonic flows
Authors: Zhang Lin , Liang Jianhan , Sun Mingbo , Yang Yue , Zhang Hailong , Cai Xiaodong
Published: February 2021

A novel scalar filtered mass density function (SFMDF) method is developed for high-speed flows, especially for supersonic reactive flows. The total energy is proposed as the energy form for SFMDF, instead of the commonly used enthalpy or sensible enthalpy. Such an energy form is entirely consistent with the one typically used in large eddy simulation (LES) for fully compressible flows, so that the exact/modeled energy equations in both LES and SFMDF are readily identical. Moreover, the total energy can formulate the SFMDF energy transport equation in such a way that the high-speed source term is strictly conservative. Following the conservative formulation, numerically robust conservative schemes are readily available for flows with discontinuities. Tests in one-dimensional Euler equations show that the temperature redundantly obtained based on the total energy (with conservative high-speed source terms) shows better agreement with the analytical result than the one based on the enthalpy. The proposed LES-SFMDF method is further tested in a shock tube interacting with an isotropic turbulent flow, a compressible two-dimensional non-reactive temporally developing mixing layer, and a supersonic three-dimensional reactive temporally developing mixing layer. Results show that SFMDF with the total energy can considerably improve the temperature distribution in both non-reactive and reactive flows. The proposed LES-SFMDF method with the total energy predicts the turbulence–chemistry interaction better than LES-SFMDF with the enthalpy as well as LES with the well-stirred reactor model in supersonic combustion. This conservative and consistent SFMDF method can be readily extended to more sophisticated probability density function methods in high-speed flows.
Ar metastable densities (3P2) in the effluent of a filamentary atmospheric pressure plasma jet with humidified feed gas
Authors: Klose S.-J. , Bansemer R. , Brandenburg R. , van Helden J. H.
Published: February 2021

The Ar(3P2) metastable density in the effluent of the cold atmospheric pressure plasma jet kINPen was investigated as a function of the feed gas humidity, the gas curtain composition, and the distance from the nozzle by means of laser atomic absorption spectroscopy. The filamentary character of the plasma jet was considered as the absorption signals are from single individual events. From the effective lifetime, the quenching coefficient for Ar(3P2) by water was determined. A maximum Ar(3P2) density of (6.0±0.7)×1013 cm−3 was obtained close to the nozzle for a feed gas humidity of 20 ppm. The densities near the nozzle decreased inversely proportional to the water content in the feed gas leveling off at approximately 1×1013 cm−3, independently from the gas curtain composition. With the addition of water to the feed gas, the excitation dynamics changed, and the production and lifetime of Ar(3P2) was reduced. The impact of Ar(3P2) on the reactive species composition in the effluent was found to be smaller than within the plasma zone inside the plasma jet device.