bluuebunny/crossref_metadata_2025 huggingface dataset:
An integrated MVDR beamformer for speech enhancement using a local microphone array and external microphones
Authors: Ali Randall , van Waterschoot Toon , Moonen Marc
Published: February 2021

An integrated version of the minimum variance distortionless response (MVDR) beamformer for speech enhancement using a microphone array has been recently developed, which merges the benefits of imposing constraints defined from both a relative transfer function (RTF) vector based on a priori knowledge and an RTF vector based on a data-dependent estimate. In this paper, the integrated MVDR beamformer is extended for use with a microphone configuration where a microphone array, local to a speech processing device, has access to the signals from multiple external microphones (XMs) randomly located in the acoustic environment. The integrated MVDR beamformer is reformulated as a quadratically constrained quadratic program (QCQP) with two constraints, one of which is related to the maximum tolerable speech distortion for the imposition of the a priori RTF vector and the other related to the maximum tolerable speech distortion for the imposition of the data-dependent RTF vector. An analysis of how these maximum tolerable speech distortions affect the behaviour of the QCQP is presented, followed by the discussion of a general tuning framework. The integrated MVDR beamformer is then evaluated with audio recordings from behind-the-ear hearing aid microphones and three XMs for a single desired speech source in a noisy environment. In comparison to relying solely on an a priori RTF vector or a data-dependent RTF vector, the results demonstrate that the integrated MVDR beamformer can be tuned to yield different enhanced speech signals, which may be more suitable for improving speech intelligibility despite changes in the desired speech source position and imperfectly estimated spatial correlation matrices.
Monotone iterative solutions for a coupled system of p-Laplacian differential equations involving the Riemann–Liouville fractional derivative
Authors: Bi Bo , He Ying
Published: February 2021

Applying the monotone iterative technique and the method of upper and lower solutions, we investigate the existence of extremal solutions for a nonlinear system of p-Laplacian differential equations with nonlocal coupled integral boundary conditions. We present a numerical example to illustrate the main result.
Ischemic small bowel perforation caused by cholesterol crystal embolism following transcatheter arterial chemoembolization for recurrent hepatocellular carcinoma: a case report
Authors: Hamura Ryoga , Haruki Koichiro , Iwase Ryota , Furukawa Kenei , Shirai Yoshihiro , Onda Shinji , Gocho Takeshi , Ikegami Toru
Published: February 2021

Background

Cholesterol crystal embolism (CCE) following transcatheter arterial chemoembolization (TACE) is rare.

Case presentation

A 71-year-old man underwent TACE for recurrence of hepatocellular carcinoma (HCC). On postoperative day (POD) 5, he developed abdominal pain and fever. Computed tomography revealed intraperitoneal free air. The patient was diagnosed with gastrointestinal perforation with peritonitis, for which partial intestinal resection and covering ileostomy were performed. Histological examination revealed perforation of the small intestine caused by CCE. The patient made a satisfactory recovery and was discharged on POD 30. The patient showed no recurrence of cholesterol crystal embolism or HCC for 2 years after surgery.

Conclusion

We reported a successfully treated case of ischemic small bowel perforation due to cholesterol crystal embolism following transcatheter arterial chemoembolization for recurrent HCC.
Could SARS-CoV-2 herald a surge of multiple sclerosis?
Authors: Shalaby Nevin Mohieldin , Shehata Hatem Samir
Published: February 2021

During the current COVID-19 pandemic, many queries are raised regarding its nature, outcome, and sequelae. This letter raises the concern of potential impact on increasing the incidence of multiple sclerosis whose pathology involves a possible viral etiology. Besides, the potential neurotropism of the acute respiratory distress syndrome corona virus-2 (SARS-CoV-2), which is still not established, may raise concerns about the use of certain disease modifying therapies namely natalizumab.
Shallow tunnel detection using converted surface waves
Authors: Peterie Shelby L. , Ivanov Julian , Knippel Erik , Miller Richard D. , Sloan Steven D.
Published: February 2021

Seismic surface waves that were likely converted from incident body waves were used to detect a 3 m deep tunnel using two novel processing methods. In data acquired at a tunnel test site, a unique forward-propagating wave (traveling away from the tunnel and seismic source) was identified as an early-arriving surface wave converted at the tunnel from an incident body wave. To our knowledge, our research represents the first time converted surface waves have been observed originating from a tunnel. We have developed two novel processing methods targeting this unique wavefield component for detecting tunnels, cavities, or other shallow anomalies. The first is a time-domain imaging method that takes advantage of the unique kinematic characteristics of converted surface waves to produce a cross section with a coherent, high-amplitude signature originating from the horizontal location of the tunnel. The second method uses frequency-domain analysis of surface-wave amplitudes, which reveals increased amplitudes (primarily from converted surface waves) at locations expected for the tunnel. These proposed approaches for analysis of converted surface waves were successfully used to detect the tunnel and accurately interpret its horizontal location in real-world data. These novel methods could be the key for detecting shallow tunnels or other subsurface anomalies and complement existing seismic detection methods.
Care Experience, by Site of Care, for Adolescents and Young Adults With Cancer
Authors: Jacobsen Rebecca L. , Macpherson Catherine Fiona , Pflugeisen Bethann Mangel , Johnson Rebecca H.
Published: February 2021

PURPOSE:

Most of the 77,000 adolescents and young adults (AYAs) 15-39 years of age diagnosed with cancer annually in the United States are treated at community rather than academic centers. Little is known about their healthcare experience.

METHODS:

A cross-sectional, anonymous, online survey was conducted with a convenience sample of AYAs treated for cancer at US academic (n = 112) or community centers (n = 64).

RESULTS:

Clinical trials were offered more frequently to respondents treated at academic centers (26.8% v 7.8%; P = .005). Eighty percent of all those offered a clinical trial chose to enroll. Over three-fourths reported awareness of community-based or online AYA oncology support services; however, significantly more respondents from academic centers reported awareness of services provided by the institution itself (40.2% v 7.8%; P < .001). Significantly more respondents from academic centers reported receiving information relevant to their age group (41.1% v 15.6%; P < .001). Respondents treated at academic centers were significantly more satisfied with support, communication, and overall treatment. Odds of respondents treated at an academic center reporting that their healthcare team knew enough about AYAs were 3.12-fold higher than those treated at community centers (95% CI, 1.6 to 6.4; P = .002). Odds of overall satisfaction were significantly higher for respondents who reported that their healthcare team “knew enough about AYAs” (aOR, 9.7, 95% CI, 2.4 to 53.9; P = .003).

CONCLUSION:

Cancer treatment for AYAs at both academic and community centers can be optimized by improving healthcare providers' understanding of the key issues facing AYAs with cancer and by increasing AYA-specific institutional resources and support services.
Cortical Bone Mass is Low in Boys with Klinefelter Syndrome and Improves with Oxandrolone
Authors: Vogiatzi Maria G , Davis Shanlee M , Ross Judith L
Published: February 2021

Context

Klinefelter syndrome (KS) is the most common sex aneuploidy in men. Affected males have hypogonadism, and, as a result, face an increased risk for osteoporosis and fractures. Androgen therapy is standard in adolescents and adults with KS but has not been used earlier in childhood.

Objective

To determine the effects of androgen treatment on bone mass in children with KS.

Methods

Randomized, double-blind, placebo-controlled clinical trial of oxandrolone (OX; 0.06 mg/kg daily; n = 38) versus placebo (PL; n = 40) for 2 years in boys with KS (ages 4-12 years). Changes in bone mass were examined by digital x-ray radiogrammetry, which determines the Bone Health Index (BHI) and standard deviation score (SDS).

Results

BHI SDS was similar between groups at baseline (–0.46 ± 1.1 vs –0.34 ± 1.0 OX vs PL, P > .05) and higher in the OX group at 2 years (–0.1 ± 1.3 vs –0.53 ± 0.9, OX vs PL, P < .01). At baseline, BHI SDS values of all subjects were not normally distributed with 25.7% of subjects plotted below –1 SDS (P < .001), suggesting a deficit in bone mass. In total, 13.5% of subjects had sustained a fracture and their BHI SDS was lower than those with no fractures (–1.6 ± 1.3 vs –0.3 ± 1.0, P = .004).

Conclusion

Bone mass using BHI SDS is reduced in some children with KS and improves with OX. Since these individuals are at risk for osteoporosis, age-appropriate androgen replacement and future studies on bone health in children with KS should be further explored.
“Reexamining the Influence of Conditional Cash Transfers on Migration From a Gendered Lens”: Comment
Authors: Stark Oded
Published: February 2021

In a recent article, “Reexamining the Influence of Conditional Cash Transfers on Migration From a Gendered Lens,” Hughes (2019) claimed that conditional cash transfers, CCT, limit the likelihood of migration by women, compensating them for giving up an attractive migration option. I question the analysis that lies behind this claim. I argue that in seeking to understand the likelihood of women migrating if they participate in a CCT program, issues of selectivity, endogeneity, and optimization cannot be set aside. In particular, it is not that receiving CCT curtails a migration option; it is that not contemplating migration encourages women to accept CCT. And if a household perspective is brought to bear, then a household's free choices weaken the appeal of migration to women. This reduction in appeal does not arise from an exogenously imposed curb but rather from endogenously determined preferences.
Visual stimulus-specific habituation of innate defensive behaviour in mice
Authors: Tafreshiha Azadeh , van der Burg Sven A. , Smits Kato , Blömer Laila A. , Heimel J. Alexander
Published: February 2021

Innate defensive responses such as freezing or escape are essential for animal survival. Mice show defensive behaviour to stimuli sweeping overhead, like a bird cruising the sky. Here, we tested this in young male mice and found that mice reduced their defensive freezing after sessions with a stimulus passing overhead repeatedly. This habituation is stimulus specific, as mice freeze again to a novel shape. Habituation occurs regardless of the visual field location of the repeated stimulus. The mice generalized over a range of sizes and shapes, but distinguished objects when they differed in both size and shape. Innate visual defensive responses are thus strongly influenced by previous experience as mice learn to ignore specific stimuli.
The frugivorous bat Carollia perspicillata dynamically changes echolocation parameters in response to acoustic playback
Authors: Beetz M. Jerome , Kössl Manfred , Hechavarría Julio C.
Published: February 2021

Animals extract behaviorally relevant signals from ‘noisy’ environments. Echolocation behavior provides a rich system testbed for investigating signal extraction. When echolocating in acoustically enriched environments, bats show many adaptations that are believed to facilitate signal extraction. Most studies to date focused on describing adaptations in insectivorous bats while frugivorous bats have rarely been tested. Here, we characterize how the frugivorous bat Carollia perspicillata adapts its echolocation behavior in response to acoustic playback. Since bats not only adapt their echolocation calls in response to acoustic interference but also with respect to target distances, we swung bats on a pendulum to control for distance-dependent call changes. Forward swings evoked consistent echolocation behavior similar to approach flights. By comparing the echolocation behavior recorded in the presence and absence of acoustic playback, we could precisely define the influence of the acoustic context on the bats' vocal behavior. Our results show that C. perspicillata decrease the terminal peak frequencies of their calls when echolocating in the presence of acoustic playback. When considering the results at an individual level, it became clear that each bat dynamically adjusts different echolocation parameters across and even within experimental days. Utilizing such dynamics, bats create unique echolocation streams that could facilitate signal extraction in noisy environments.
Parallel evolution of placental calcium transfer in the lizard Mabuya and eutherian mammals
Authors: Hernández-Díaz Nathaly , Leal Francisca , Ramírez-Pinilla Martha Patricia
Published: February 2021

An exceptional case of parallel evolution between lizards and eutherian mammals occurs in the evolution of viviparity. In the lizard genus Mabuya, viviparity provided the environment for the evolution of yolk-reduced eggs and obligate placentotrophy. One major event that favored the evolution of placentation was the reduction of the eggshell. As with all oviparous reptiles, lizard embryos obtain calcium from both the eggshell and egg yolk. Therefore, the loss of the eggshell likely imposes a constraint for the conservation of the egg yolk, which can only be obviated by the evolution of alternative mechanisms for the transport of calcium directly from the mother. The molecular and cellular mechanisms employed to solve these constraints, in a lizard with only a rudimentary eggshell such as Mabuya, are poorly understood. Here, we used RT-qPCR on placental and uterine samples during different stages of gestation in Mabuya, and demonstrate that transcripts of the calcium transporters trpv6, cabp28k, cabp9k and pmca are expressed and gradually increase in abundance through pregnancy stages, reaching their maximum expression when bone mineralization occurs. Furthermore, CABP28K/9K proteins were studied by immunofluorescence, demonstrating expression in specific regions of the mature placenta. Our results indicate that the machinery for calcium transportation in the Mabuya placenta was co-opted from other tissues elsewhere in the vertebrate bodyplan. Thus, the calcium transportation machinery in the placenta of Mabuya evolved in parallel with the mammalian placenta by redeploying the expression of similar calcium transporter genes.
Ο ρόλος της βίωσης των θετικών συναισθημάτων στην ομαδική αποτελεσματικότητα
Authors: Γαλανάκης Μιχάλης , Σταλίκας Αναστάσιος
Published: February 2021

The abstract is available in the PDF
Το υποκειμενικό στρες και η ικανοποίηση από τη ζωή ως ενδιάμεσες μεταβλητές στη σχέση μεταξύ γενικευμένων προσδοκιών και υγείας
Authors: Χ. Καραδήμας Ευάγγελος
Published: February 2021

The abstract is available in the PDF
Η μέτρηση του κοινωνικο-οικονομικού επιπέδου: Μια εναλλακτική μεθοδολογική και στατική προσέγγιση
Authors: Μυλωνάς Κώστας , Ξανθοπούλου Χρυσάνθη
Published: February 2021

The abstract is available in the PDF
Η επίδραση της νικοτίνης στις επιδόσεις της μνήμης και στην ηλεκτροφυσιολογική διαμόρφωση του P300
Authors: Β. Καραπέτσας Αργύρης , Χ. Ζυγούρης Νίκος
Published: February 2021

The abstract is available in the PDF
The use of a rote learning strategy in Greek inflectional spelling
Authors: Chliounaki Kalliopi , Bryant Peter
Published: February 2021

THE ABSTRACT IS AVAILABLE IN THE PDF
Νόημα ζωής: συγκριτική μελέτη μεταξύ ατόμων χαμηλής, μέτριας και υψηλής καταθλιπτικής συμπτωματολογίας
Authors: Κλεφτάρας Γιώργος , Ψαρρά Ευαγγελία , Καλαντζή - Αζίζι Αναστασία
Published: February 2021

The abstract is available in the PDF
Διαπολιτισμική συνεργασία και συνεργίες. Κίνητρα και προϋποθέσεις επιτυχίας
Authors: Γρέβιας Δημήτριος
Published: February 2021

The abstract is available in the PDF
Στίγμα και ψυχική διαταραχή: Ο δρόμος προς τον αποστιγματισμό
Authors: Οικονόμου Μαρίνα , Γραμανδάνη Χριστίνα , Λουκή Ελένη , Γιώτης Λάμπρος , Στεφάνης Κώστας
Published: February 2021

The abstract is available in the PDF
Αξίες και οικογένεια: Μια διαπολιτισμική μελέτη
Authors: Γιώτσα Άρτεμις
Published: February 2021

The abstract is available in the PDF
Recidivism among juvenile delinquents: Self-reported sociodemografic characteristics, behavioural features and perceptions of delinquency
Authors: Kiriakidis Stavros P.
Published: February 2021

THE ABSTRACT IS AVAILABLE IN THE PDF
Φόβος επιτυχίας, φόβος αποτυχίας και προσανατολισμός στο στόχο
Authors: Μάντη Ειρήνη , Δ. Σιδερίδης Γεώργιος
Published: February 2021

The abstract is available in the PDF
Πάσχοντας από υπογονιμότητα
Authors: De Parseval Genevieve Delaisi
Published: February 2021

The abstract is available in the PDF
Αναπαραστάσεις περιβαλλοντικών συγκρούσεων: Η από κοινού δόμηση ενός ορισμού της σύγκρουσης από τα εμπλεκόμενα μέρη
Authors: Σίμωση Μαρία
Published: February 2021

The abstract is available in the PDF
Μετρώντας την έννοια της κουλτούρας των οργανισμών: Το ερωτηματολόγιο Οργανωτικής Κουλτούρας
Authors: Ξενικού Αθηνά
Published: February 2021

The abstract is available in the PDF
Οι αντιλήψεις των εφήβων για τις σχέσεις προσκόλλησης με γονείς και συνομηλίκους ως παράγοντας πρόβλεψης της επιθετικότητας στην εφηβεία
Authors: Μακρή-Μπότσαρη Εύη
Published: February 2021

The abstract is available in the PDF
Όψεις της ανάπτυξης των διδύμων
Authors: Μαρκοδημητράκη Μαρία , Κουγουμουτζάκης Γιάννης , Κοκκινάκη Θεανώ
Published: February 2021

The abstract is available in the PDF
Θεωρίες σχηματισμού συγκεκριμένων εννοιών
Authors: Ζιώρη Ελένη
Published: February 2021

The abstract is available in the PDF
Προσδοκίες αυτοαποτελεσματικότητας και καταθλιπτικά συμπτώματα: Άμεσες και έμμεσες σχέσεις
Authors: Χ. Καραδήμας Ευάγγελος
Published: February 2021

The abstract is available in the PDF
Aportes del feminismo jurídico a la justicia transicional
Authors: Sánchez Moreno Manuel
Published: February 2021

El feminismo jurídico surge de las luchas por los derechos humanos, y, concretamente, los derechos de las mujeres y la diversidad afectivo-sexual en el marco de una teoría crítica que ha modificado la forma en la que se interpreta el derecho. Identidades previamente excluidas reclaman ahora una presencia mayor y desarrollan herramientas para demostrar su desprotección e invisibilización ante el derecho. Partiendo de las propuestas teóricas feministas, se analizan las principales causas de este sesgo legal, como la forclusión o el fundacionalismo. También se retomarán elementos que consideramos clave para huir de un análisis esencialista, como la interseccionalidad, la inclusión de las personas lgtbiqa+ o las manifestaciones del sexismo. Desarrollaremos así una metodología jurídica feminista, que contrastaremos con las dimensiones de la justicia transicional y la lucha contra la impunidad: justicia, verdad, reparación y no repetición. Finalmente, este desarrollo teórico se ilustrará, en clave de género, con algunos casos emblemáticos, como la violencia sexual en tribunales internacionales, los juicios por delitos de lesa humanidad en Argentina o la querella argentina por los crímenes del franquismo.
depuración étnica en el derecho internacional: entre el derecho penal internacional y la responsabilidad de proteger
Authors: Pezzano Luciano
Published: February 2021

La inclusión de la depuración étnica, un concepto que carece de significado jurídico propio en el derecho internacional, dentro del ámbito material de la responsabilidad de proteger, junto a crímenes bien tipificados en el derecho penal internacional, ha dado lugar a ciertas dificultades conceptuales. Este ensayo busca explorar, a través de la caracterización de la depuración étnica en el derecho internacional y, en particular, de sus posibles configuraciones como crímenes según el derecho penal internacional, los problemas que esa inclusión a primera vista anómala puede plantear en la interpretación del alcance material de esta. Con tal fin, se aborda el nacimiento y evolución del concepto de la depuración étnica en las relaciones internacionales y en su consideración por los órganos de las Naciones Unidas; se lo analiza luego a la luz del derecho penal internacional, para determinar si puede constituir uno o más de los crímenes internacionales reconocidos, teniendo en cuenta la jurisprudencia internacional y las normas aplicables; finalmente, se estudia la inclusión de la depuración étnica en el ámbito de la responsabilidad de proteger y los problemas que plantea, para elaborar una posible alternativa de solución a partir de los resultados del análisis
desaparición forzada de la identidad
Authors: Vanyó Vicedo Raquel
Published: February 2021

Esta investigación pretende denunciar la impunidad de uno de los crímenes más atroces del Estado español como es la desaparición forzada de miles de niños que fueron arrebatados a sus madres, primero como castigo ideológico e instrumento represivo de depuración eugenésica instaurado por el franquismo y que, convertido después en un lucrativo negocio de compraventa de menores, acaba moviendo a su antojo los hilos de la filiación en España hasta bien entrada la democracia.

Pese a que los numerosos casos denunciados en los últimos años apuntan a que podríamos estar ante un verdadero crimen de lesa humanidad, las autoridades españolas, tanto gubernamentales como judiciales, no permiten investigar estos hechos, al igual que otras muchas de las violaciones de derechos humanos que se cometieron durante la dictadura, de manera que, a día de hoy, la única esperanza de las víctimas para acceder a la verdad, la justicia y la reparación está depositada en la justicia penal internacional.
Life with half a heart: the early years
Authors: McStay Linda
Published: February 2021

In this month's patient story, Linda McStay describes her early life as an individual born with a univentricular heart and how it felt to undergo Fontan surgery at 10 years of age.
Keeping perspective as a nurse amid a pandemic
Authors: Quinn Charlotte
Published: February 2021

A registered nurse on the coronary care unit, and now completing her Postgraduate Diploma in Specialist Practice Nursing Cardiology at Queen's University Belfast, Charlotte Quinn reflects on the importance of nursing care, particularly amid the challenges of the COVID-19 pandemic.
Running a one-stop clinic for patients with inflammatory bowel disease
Authors: Carriss-Wright Julie
Published: February 2021

Julie Carriss-Wright, Clinical Nurse Specialist, IBD, The Mid Yorkshire Hospitals NHS Trust ( julie.carriss-wright@nhs.net ), runner-up in the BJN Awards 2020 Gastrointestinal/IBD Nurse of the Year category
Judging mental capacity to engage safely with social media
Authors: Griffith Richard
Published: February 2021

Richard Griffith, Senior Lecturer in Health Law at Swansea University, discusses recent cases from the Court of Protection that have focused on a person's mental capacity to engage safely with social media
Exploring multiple paths
Authors: Bandali Mahdiyah
Published: February 2021

Since graduating as a newly qualified paramedic in June amid COVID-19, Mahdiyah Bandali has chosen the unconventional path of exploring multiple avenues within paramedicine and, in her first contribution, shares her reflections and lessons learned on this journey to date
Droplet Size Spectrum, Activation Pressure, and Flow Rate Discharged from PWM Flat-Fan Nozzles
Authors: Wei Zhiming , Zhu Heping , Zhang Zhihong , Salcedo Ramón , Duan Degang
Published: February 2021

Highlights

Droplet sizes, activation pressures acting on nozzle orifices, and flow rates were investigated.

Droplet sizes varied with duty cycles, nozzle orifice sizes, and PWM solenoid valve manufacturers.

Activation pressures decreased as duty cycles decreased and increased as nozzle orifice sizes decreased.

Flow rates increased with increases in both duty cycles and nozzle orifice sizes.

Abstract. Pulse width modulated (PWM) spray systems can produce variable spray rates for precision applications of pesticide and fertilizer; however, there are also concerns over their spray performance stability. Droplet size distributions, activation pressures acting on nozzle orifices, and flow rates discharged from nozzles were investigated for test combinations of ten PWM duty cycles (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%), six flat-fan nozzles with different orifice sizes (XR8001, XR8002, XR8003, XR8004, XR8005, and XR8006), and two PWM solenoid valves from two different manufacturers. Test results showed that the droplet size distribution, activation pressure, and flow rate varied with the duty cycle, nozzle orifice size, and PWM solenoid valve source. For XR8001 and XR8002 nozzles, droplet sizes did not vary significantly with all duty cycles from 10% to 100%. To obtain relatively consistent droplet size distributions, XR8003 and XR8004 nozzles required PWM duty cycles of at least 20%, while XR8005 and XR8006 nozzles required duty cycles of 30% or greater. The activation pressure directly on nozzle orifices increased as the duty cycle increased but decreased as the nozzle orifice size increased. In addition, the same nozzles coupled with PWM solenoid valves from two different manufacturers discharged different flow rates for the same duty cycle in the range of 10% to 90%. Therefore, careful selection of PWM solenoid valves for different orifice nozzles operated at different duty cycles was necessary to achieve consistent variable-rate spray performances. Keywords: Droplet diameter, Variable rate, PWM solenoid valve, Pesticide, Fertilizer, Precision farming.
Guiding the young child: trajectories of parents’ educational work in Singapore
Authors: Göransson Kristina
Published: February 2021

Singapore has established a reputation as a top performer in international student assessment tests and rankings, which is usually understood to be the result of a competitive education system and a distinct Asian parenting culture. Drawing on ethnographic data, the aim of the article is to explore the emotional and moral dimensions of Singaporean parents’ educational work, and how they cope with complex and sometimes contradictory demands in raising their young children. The article is based on interviews and observations with parents of pre- and primary school-aged children. The reasons for focusing specifically on this category of parents was that previous research indicates that parental involvement in children’s education in Singapore is most intense during this period, and that parents everywhere are faced with increasing expectations to attend to their young children’s learning and cognitive development. The findings contest simplistic interpretations of intensive parenting in East Asia, especially when considering the role of social class, gender and generational change.
Subchannel and Power Allocation for NOMA- Based Satellite Networks
Authors: Liu Qingyuan , Zhang Qi , Shen Yufei , Tao Ying , Chen Dong , Zhang Wei , Tian Feng , Tian Qinghua , Wang Yongjun , Yang Leijing
Published: February 2021

A resource allocation method based on matching theory and a difference-of-two-convex-functions programming approach is proposed for satellite networks. Numerical results show that this method can balance system capacity and user fairness.
Satellite Backbone Ring Network with Ω-topology based on Sparse Configuration Arrayed Waveguide Grating
Authors: Li Yang , Zhu Yixiao , Li Longsheng , Guo Zidong , Hu Weisheng
Published: February 2021

A novel architecture for satellite backbone network with Ω-topology is presented, where the ROADM nodes are based on arrayed waveguide grating with loop-back optical paths.
The Effectively Corrected Scheme for Polarization De-multiplexing in Tight Time-Packing PDM-FTN Optical Communication System with Extreme Polarization Impairments
Authors: Sun Peng , Zhang Xiaoguang , Xi Lixia , Zhang Wenbo , Tang Xianfeng
Published: February 2021

We propose an effectively corrected scheme for polarization de-multiplexing algorithms in tight time-packing factor which is equal to 0.5 PDM-FTN-QPSK system with extreme polarization impairments which contain ultra-fast RSOP and large PMD.
A Bonding Structure with Low Return Loss and High Transmission Bandwidth for Microwave Circuit
Authors: Sun Shangbin , Chen Yuanxiang , Fu Jia , Han Ying , Huang Yongtao , Lin Shangjing , Yang Leijing , Yu Jianguo
Published: February 2021

In this paper, we present a bonding interconnect structure based on multi-stub impedance matching. The proposed structure has excellent high-frequency performance with 3dB bandwidth of 65.9 GHz and return loss of -15.533dB at 40 GHz.
P4-Enabled Smart NIC for Intra-Server Network Virtualization Acceleration
Authors: Yan Yan , Zhuang Jianlin , Nejabati Reza , Simeonidou Dimitra
Published: February 2021

We implemented OVS data plane offload on P4-enabled Smart NIC, which enabled accelerating the server virtualization flexibly. The results showed, with Smart NIC enabled OVS offload, the bandwidth increased 4x and CPU utilization decreased 70%.
A compact optics embedded optical receiver engine mounted on silicon interposer for 400G CWDM4 10km data center application
Authors: Lee Jyung Chan , Lee Eun-Gu , Yeom Jubin , Jeon Kyeongwan , Kang Changhyun , Moon Jong Ha
Published: February 2021

We proposed a new conceptual tiny optical engine. With optimization of direct optical coupling between PDs and PLC-AWG, the compact optics embedded optical receiver engine mounted on silicon interposer was applicable for 400G CWDM4 10km
Laser acquisition experimental demonstration for space gravitational wave detection missions
Authors: Gao Ruihong , Liu Heshan , Zhao Ya , Luo Ziren , Shen Jia , Jin Gang
Published: February 2021

The laser acquisition-pointing technique is one of the most important techniques for space gravitational wave detection missions, like the Taiji program and the LISA (Laser Interferometer Space Antenna) program. The laser acquisition system suppresses the laser deviation angle to 1 µrad at the receiving aperture. Corresponding to 80 times of telescope magnification, the acquisition accuracy should reach 80 µrad at the acquisition camera. In order to verify the feasibility of the laser acquisition scheme, a laser acquisition ground simulation experimental system is designed and constructed. The experimental system simulates the actual acquisition process of the Taiji from three aspects: optical path, acquisition accuracy and acquisition scanning process. In the experiment, the coupling between the laser acquisition system and the laser pointing system is considered by introducing the DWS (Differential Wave-front Sensing) technique to calibrate the reference position of the acquisition camera and read out the acquisition precision. Due to limited beam propagation distance in the ground experiment, the in-flat top properties of the transmitting beam will greatly affect the acquisition precision. Based on the analysis of the influence, an improved acquisition ground simulation scheme is introduced. The experimental results indicate that the experimental system can achieve the acquisition accuracy of sub-10 µrad magnitude at the acquisition camera. The experimental system realizes methodological demonstration of the acquisition scheme. The results offer the experimental foundation and theoretical basis for the acquisition system of the Taiji/LISA program.
High-frequency broadband laser phase noise cancellation using a delay line
Authors: Parniak Michał , Galinskiy Ivan , Zwettler Timo , Polzik Eugene S.
Published: February 2021

Laser phase noise remains a limiting factor in many experimental settings, including metrology, time-keeping, as well as quantum optics. Hitherto this issue was addressed at low frequencies ranging from well below 1 Hz to maximally 100 kHz. However, a wide range of experiments, such as, e.g., those involving nanomechanical membrane resonators, are highly sensitive to noise at higher frequencies in the range of 100 kHz to 10 MHz, such as nanomechanical membrane resonators. Here we employ a fiber-loop delay line interferometer optimized to cancel laser phase noise at frequencies around 1.5 MHz. We achieve noise reduction in 300 kHz-wide bands with a peak reduction of more than 10 dB at desired frequencies, reaching phase noise of less than −160 dB(rad2/Hz) with a Ti:Al2O3 laser. These results provide a convenient noise reduction technique to achieve deep ground-state cooling of mechanical motion.
High efficiency tunable unidirectional single-longitudinal-mode Er:YAG ring laser based on an acousto-optic modulator
Authors: Huang Shuai , Chen Chaoyong , Wang Kaixin , Zhang Xu , Wang Qing , Gao Chunqing
Published: February 2021

A wavelength tunable single-longitudinal-mode (SLM) Er:YAG ring laser around 1.6 µm is demonstrated. By using an acousto-optic modulator (AOM) to force unidirectional operation, up to 10.4 W and 8.7 W SLM laser output power are obtained at 1645.22 nm and 1617.33 nm, with corresponding slope efficiencies of 45% and 40%, respectively. Besides, stable dual-wavelength operation at both 1645 nm and 1617 nm is also achieved with the maximum power of 9.1 W. By rotating the birefringent filter (BRF) in the ring cavity, the wavelength could be tuned from 1616.77 nm to 1617.51 nm and 1644.51 nm to 1646.12 nm. The line width is measured to be 125 kHz at 1617 nm and 131 kHz at 1645 nm via the time-delayed self-heterodyne method. As far as we know, 8.7 W is the highest continuous-wave SLM output power at 1617 nm.
Optical pumping of quantum dot micropillar lasers
Authors: Andreoli L. , Porte X. , Heuser T. , Große J. , Moeglen-Paget B. , Furfaro L. , Reitzenstein S. , Brunner D.
Published: February 2021

Arrays of quantum dot micropillar lasers are an attractive technology platform for various applications in the wider field of nanophotonics. Of particular interest is the potential efficiency enhancement as a consequence of cavity quantum electrodynamics effects, which makes them prime candidates for next generation photonic neurons in neural network hardware. However, particularly for optical pumping, their power-conversion efficiency can be very low. Here we perform an in-depth experimental analysis of quantum dot microlasers and investigate their input-output relationship over a wide range of optical pumping conditions. We find that the current energy efficiency limitation is caused by disadvantageous optical pumping concepts and by a low exciton conversion efficiency. Our results indicate that for non-resonant pumping into the GaAs matrix (wetting layer), 3.4% (0.6%) of the optical pump is converted into lasing-relevant excitons, and of those only 2% (0.75%) provide gain to the lasing transition. Based on our findings, we propose to improve the pumping efficiency by orders of magnitude by increasing the aluminium content of the AlGaAs/GaAs mirror pairs in the upper Bragg reflector.
Silicon nitride PIC-based multi-color laser engines for life science applications
Authors: Mashayekh Alireza Tabatabaei , Klos Thomas , Geuzebroek Douwe , Klein Edwin , Veenstra Theo , Büscher Martin , Merget Florian , Leisching Patrick , Witzens Jeremy
Published: February 2021

We implement a multi-color laser engine with silicon nitride photonic integrated circuit technology, that combines four fluorophore excitation wavelengths (405 nm, 488 nm, 561 nm, 640 nm) and splits them with variable attenuation among two output fibers used for different microscope imaging modalities. With the help of photonic integrated circuit technology, the volume of the multi-color laser engine’s optics is reduced by two orders of magnitude compared to its commercially available discrete optics counterpart. Light multiplexing is implemented by means of a directional coupler based device and variable optical attenuation as well as fiber switching with thermally actuated Mach-Zehnder interferometers. Total insertion losses from lasers to output fibers are in the order of 6 dB at 488 nm, 561 nm, and 640 nm. Higher insertion losses at 405 nm can be further improved on. In addition to the system level results, spectrally resolved performance has been characterized for each of the developed devices.
Two-dimensional spectral signal model for chromatic confocal microscopy
Authors: Chen Cheng , Leach Richard , Wang Jian , Liu Xiaojun , Jiang Xiangqian , Lu Wenlong
Published: February 2021

In chromatic confocal microscopy, the signal characteristics influence the accuracy of the signal processing, which in turn determines measurement performance. Thus, a full understanding of the spectral characteristics is critical to enhance the measurement performance. Existing spectral models only describe the signal intensity-wavelength characteristics, without taking the displacement-wavelength relation into consideration. These models require prior knowledge of the optical design, which reduces the effectiveness in the optical design process. In this paper, we develop a two-dimensional spectral signal model to describe the signal intensity-wavelength-displacement characteristics in chromatic confocal microscopy without prior knowledge of the optical design layout. With this model, the influence of the dimensional characteristics of the confocal setup and the displacement-wavelength characteristics and monochromatic aberrations of the hyperchromatic objective are investigated. Experimental results are presented to illustrate the effectiveness of our signal model. Using our model, further evaluation of the spectral signal can be used to enhance the measurement performance of chromatic confocal microscopy.
Compact all-fiber thermo-optic modulator based on a Michelson interferometer coated with NaNdF4 nanoparticles
Authors: Bo Yutao , Guan Chunying , Chu Rang , Cheng Tailei , Xu Li , Liu Lu , Yang Jing , Shi Jinhui , Wang Pengfei , Yang Jun , Yuan Libo
Published: February 2021

We propose and investigate an all-fiber thermo-optic modulator based on a side-polished twin-core fiber (TCF) Michelson interferometer (MI) coated with NaNdF4 nanoparticles. The MI was fabricated by tapering the splicing point between the TCF and a single mode fiber (SMF). A short suspended core fiber (SCF) is spliced to one core of the TCF to introduce a fixed optical phase difference (OPD). The side-polished core is coated with photo-thermal material NaNdF4. Owing to the ohmic heating of NaNdF4 nanoparticles under 808 nm pump laser, the effective refractive index of the polished core is changed, resulting in a phase shift of the MI. The MI has a significant modulation phase shift with 2.9 π near the wavelength of 1260 nm and can obtain an optical switching with a rise (fall) time of 152 (50) ms. The proposed device will have a great application potential in optical modulators due to compact structure and strong robustness.
Dynamic sampling iterative phase retrieval for holographic data storage
Authors: Chen Ruixian , Hao Jianying , Yu Changyu , Zheng Qijing , Qiu Xianying , Wang Suping , Chen Yuxin , Wang Kun , Lin Dakui , Yang Yi , Li Hui , Lin Xiao , Tan Xiaodi
Published: February 2021

A dynamic sampling iterative phase retrieval method, which dynamically samples the Fourier intensity distribution of the reconstruction beam captured by the detector, is proposed to shorten the iterative number and decrease the phase error rate of phase retrieval in the phase-modulated holographic data storage. By the dynamic sampling method, that keeping relatively low frequency component of Fourier intensity spectrum at the beginning of iteration and gradually releasing more high frequency component at the subsequent iterations, we shortened the iterative number by 2 times and decreased the phase error rate to some extent because our method provided a better convergent path to the phase retrieval. We also believe the thought of our method can be used in more image retrieval fields.
Multifunctional full-space metasurface controlled by frequency, polarization and incidence angle
Authors: Zhang Zhongtao , Wang Jiafu , Zhu Ruichao , Jia Yuxiang , Liu Tonghao , Yan Mingbao , Jiang Jinming , Li Yongfeng , Meng Yueyu , Qu Shaobo
Published: February 2021

Multifunctional metasurfaces have exhibited considerable abilities of manipulating electromagnetic (EM) waves, especially in full-space manipulation. However, most works are implemented with functions controlled by polarization or frequency and seldom involve the incidence angle. Herein, we propose a multifunctional full-space metasurface controlled by frequency, polarization and incidence angle. A meta-atom is firstly designed. When EM waves illumine normally in the C-band, it possesses the characteristic of asymmetric transmission with high-efficient polarization conversion. In the Ku-band, both x- and y-polarized EM waves along both sides will be reflected and achieve broadband and high-efficient cross-polarization conversion. Also, when illumined obliquely, both sides can achieve efficient retroreflection at a certain frequency. As a proof of concept, a metasurface consisting of the above meta-atoms is configured as a dual orbital angular momentum (OAM) vortex beam generator and different beam deflector when illumined normally. Meanwhile, it acts as a multi-channel retroreflector when illumined obliquely. Both the simulated and measured results show excellent performances. Our findings provide a new degree of freedom to design multifunctional metasurfaces that can further promote applications.
Design of an on-chip electrically driven, position-adapted, fully integrated erbium-based waveguide amplifier for silicon photonics
Authors: Zhou Peiqi , Wang Bo , Wang Xingjun , Wang Bing , He Yandong , Bowers John E.
Published: February 2021

Erbium-doped waveguide amplifiers are important for silicon photonic large-scale integration. They boost the optical signal to compensate for the on-chip loss of the whole system, such as insertion, transmission, and coupling loss. Herein, a GaAs-on-silicon-pumped erbium-based waveguide amplifier is proposed. The optical amplifier is based on waveguides evanescently coupled with an erbium-doped thin-film gain medium. The erbium-doped gain region is locally pumped by a hybrid GaAs-SiN/SiO vertical-cavity-emitting pump laser. It can be selectively fabricated on the silicon photonic chip that has good position flexibility when integrated with other devices. The amplifier provides high-quality electrically driven amplification and realizes the full integration of amplifiers with the silicon photonic system without any external pump light source. The modeling analyses show that the proposed amplifier design has a maximum saturated gain of 42.5 dB/cm with a modulation bandwidth of ∼42 GHz. This high-gain, large-bandwidth device fully utilizes the advantages of erbium-doped materials and silicon-based III-V semiconductors, while overcoming their issues, and opens up a new pathway for on-chip amplification.
Unraveling ChR2-driven stochastic Ca2+ dynamics in astrocytes: A call for new interventional paradigms
Authors: Moshkforoush Arash , Balachandar Lakshmini , Moncion Carolina , Montejo Karla A. , Riera Jorge
Published: February 2021

Optogenetic targeting of astrocytes provides a robust experimental model to differentially induce Ca2+ signals in astrocytes in vivo. However, a systematic study quantifying the response of optogenetically modified astrocytes to light is yet to be performed. Here, we propose a novel stochastic model of Ca2+ dynamics in astrocytes that incorporates a light sensitive component—channelrhodopsin 2 (ChR2). Utilizing this model, we investigated the effect of different light stimulation paradigms on cells expressing select variants of ChR2 (wild type, ChETA, and ChRET/TC). Results predict that depending on paradigm specification, astrocytes might undergo drastic changes in their basal Ca2+ level and spiking probability. Furthermore, we performed a global sensitivity analysis to assess the effect of variation in parameters pertinent to the shape of the ChR2 photocurrent on astrocytic Ca2+ dynamics. Results suggest that directing variants towards the first open state of the ChR2 photocycle (o1) enhances spiking activity in astrocytes during optical stimulation. Evaluation of the effect of Ca2+ buffering and coupling coefficient in a network of ChR2-expressing astrocytes demonstrated basal level elevations in the stimulated region and propagation of calcium activity to unstimulated cells. Buffering reduced the diffusion range of Ca2+ within the network, thereby limiting propagation and influencing the activity of astrocytes. Collectively, the framework presented in this study provides valuable information for the selection of light stimulation paradigms that elicit desired astrocytic activity using existing ChR2 constructs, as well as aids in the engineering of future application-oriented optogenetic variants.
Establishment of an in vitro culture system to study the developmental biology of Onchocerca volvulus with implications for anti-Onchocerca drug discovery and screening
Authors: Gandjui Narcisse V. T. , Njouendou Abdel J. , Gemeg Eric N. , Fombad Fanny F. , Ritter Manuel , Kien Chi A. , Chunda Valerine C. , Fru Jerome , Esum Mathias E. , Hübner Marc P. , Enyong Peter A. , Hoerauf Achim , Wanji Samuel
Published: February 2021

Background

Infections with Onchocerca volvulus nematodes remain a threat in Sub-Saharan Africa after three decades of ivermectin mass drug administration. Despite this effort, there is still an urgent need for understanding the parasite biology especially the mating behaviour and nodule formation as well as the development of more potent drugs that can clear the developmental (L3, L4, L5) and adult stages of the parasite and inhibit parasite reproduction and behaviour.

Methodology/Principal findings

Prior to culture, freshly harvested O. volvulus L3 larvae from dissected Simulium damnosum flies were purified by centrifugation using a 30% Percoll solution to eliminate fly tissue debris and contaminants. Parasites were cultured in both cell-free and cell-based co-culture systems and monitored daily by microscopic visual inspection. Exhausted culture medium was replenished every 2–3 days. The cell-free culture system (DMEM supplemented with 10% NCS) supported the viability and motility of O. volvulus larvae for up to 84 days, while the co-culture system (DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells) extended worm survival for up to 315 days. Co-culture systems alone promoted two consecutive parasite moults (L3 to L4 and L4 to L5) with highest moulting rates (69.2±30%) observed in DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells, while no moult was observed in DMEM supplemented with 10% NCS and seeded on LEC feeder cells. In DMEM supplemented with 10% FBS and seeded on LLC-MK2 feeder cells, O. volvulus adult male worms attached to the vulva region of adult female worms and may have mated in vitro. Apparent early initiation of nodulogenesis was observed in both DMEM supplemented with 10% FBS and seeded on LLC-MK2 and DMEM supplemented with 10% NCS and seeded on LLC-MK2 systems.

Conclusions/Significance

The present study describes an in vitro system in which O. volvulus L3 larvae can be maintained in culture leading to the development of adult stages. Thus, this in vitro system may provide a platform to investigate mating behaviour and early stage of nodulogenesis of O. volvulus adult worms that can be used as additional targets for macrofilaricidal drug screening.