bluuebunny/crossref_metadata_2025 huggingface dataset:
Cover-aware Steganalysis
Authors: Bunzel Niklas , Steinebach Martin , Liu Huajian
Published: April 2021

The increasing digitization offers new ways, possibilities and needs for a secure transmission of information. Steganography and its analysis constitute an essential part of IT-Security. In this work we show how methods of blind-steganalysis can be improved to work in cover-aware scenarios, we will call this non-blind steganalysis. The main objective was to examine how to take advantage of the knowledge of reference images to maximize the accuracy-rate of the analysis.

Therefore we evaluated common stego-tools and their embedding algorithms and established a dataset of 353110 images. The images have been applied to test the potency of the improved methods of the non-blind steganalysis. The results show that the accuray can be significantly improved by using cover-images to produce reference images. Also the aggregation of the outcomes has shown to have a positive impact on the accuracy. Particularly noteworthy is the correlation between the qualities of the stego- and coverimages. Only by consindering both, the accuracy could strongly be improved. Interestingly the difference between both qualities also has a deep impact on the results.
Post-quantum MACsec in Ethernet Networks
Authors: Cho Joo Yeon , Sergeev Andrew
Published: April 2021

The demand on MACsec in Ethernet is increasing substantially since MACsec fits well for industrial applications which require strong security as well as efficiency. To provide a long-term security, the MACsec protocol should be resistant to future attacks including quantum attacks. In this paper, MACsec is analysed under a quantum attack scenario. To achieve 128-bit quantum security, AES (Advanced Encryption Standard) algorithms defined in MACsec should mandate to use 256-bit keys. On the other hand, classical public-key cryptosystems in MKA are not secure at all against quantum attacks so that they need to be replaced by post-quantum crypto schemes in a quantum world. We propose an authenticated post-quantum key establishment protocol which is suitable for long-term secure MACsec. The proposed protocol is used in the hybrid mode, an ephemeral key exchange, and an end-to-end encryption. We verified by experiments that the proposed protocol can be deployed in existing a MACsec-enabled Ethernet network.
A Review and Case Study on Android Malware: Threat Model, Attacks, Techniques and Tools
Authors: Negi Charu , Mishra Preeti , Chaudhary Pooja , Vardhan Harsh
Published: April 2021

As android devices have increased in number in the past few years, the android operating system has started dominating the smartphone market. The vast spread of android across all the devices has made security an important issue as the android users continue to grow exponentially. The security of android platform has become the need of the hour in view of increase in the number of malicious apps and thus several studies have emerged to present the detection approaches. In this paper, we review the android components to propose a threat model that illustrates the possible threats that are present in the android. We also present the attack taxonomy to illustrate the possible attacks at various layers of the android architecture. Experiments demonstrating the feature extraction and classification using machine earning algorithms have also been performed.
User Privacy and Data Flow Control for Android Apps: Systematic Literature Review
Authors: Alkindi Zainab Rashid , Sarrab Mohamed , Alzeidi Nasser
Published: April 2021

Android mobile apps gain access to numerous users’ private data. Users of different Android mobile apps have less control over their sensitive data during their installation and run-time. Too often, these apps consider data privacy less serious than users’ expectations. Many mobile apps misbehave and upload users’ data without permission which confirmed the possibility of privacy leakage through different network channels. The literature has proposed various approaches to protect user’s data and avoid privacy violations. In this paper, we provide a comprehensive overview of state-of-art research on Android user privacy, and data flow control. the aim is to highlight the main trends, pinpoint the main methodologies applied, and enumerate the privacy violations faced by Android users. We also shed some light on the directions where the researcher’s community effort is still needed. To this end, we conduct a Systematic Literature Review (SLR) during which we surveyed 114 relevant research papers published in leading conferences and journals. Our thorough examination of the relevant literature has led to a critical analysis of the proposed solutions with a focus on user privacy extensions and mechanism for the Android mobile platform. Furthermore, possible solutions and research directions have been discussed.
Automatic Detection of HTTP Injection Attacks using Convolutional Neural Network and Deep Neural Network
Authors: Odumuyiwa Victor , Chibueze Analogbei
Published: April 2021

HTTP injection attacks are well known cyber security threats with fatal consequences. These attacks initiated by malicious entities (either human or computer) send dangerous or unsafe malicious contents into the parameters of HTTP requests. Combatting injection attacks demands for the development of Web Intrusion Detection Systems (WIDS). Common WIDS follow a rule-based approach or a signature-based approach which have the common problem of high false-positive rate (wrongly classifying malicious HTTP requests) hence making them restricted to only one type of web application. They are easily bypassed and unable to detect new kinds of malicious attacks as they lack a sufficient model of understanding the representations of HTTP request parameters. In this paper, deep learning techniques are used to develop models that would automatically detect injection attacks in HTTP requests. A special layer called the character embedding layer in the deep learning models is used to allow the learning of the representation of the request parameter of HTTP requests in higher abstract levels and also aid in learning the relationships between the characters of the request parameter. The experimentation results showed that with deep learning, better injection attack detection is possible and given the right dataset, a deep learning detection model would be able to correctly classify HTTP requests for any web application.
Enhanced AIS Based Intrusion Detection System Using Natural Killer Cells
Authors: Bejoy B. J. , Janakiraman S.
Published: April 2021

Intrusion detection system is used to monitor the system and network activities to identify anomalies and attacks so that integrity, availability, and confidentiality can be preserved. Here an intrusion detection system based on Artificial Immune System is proposed based on Natural Killer (NK) cells with immunological memory. NK cells are created and each NK cells detection radius is determined using the negative selection algorithm and is trained to detect various attacks. Effective cells with high fairness values are proliferated and distributed to the network using clonal selection algorithm. In this paper, two types of NK cell are used-a Heavyweight NK cell (HWNK) and a number of Lightweight NK cells (LWNK). The incoming data is vectorized and Major Histocompatibility Complex Class I (MHC1) is created. Then based on this MHC1, any of the receptors i.e. Activating Receptor or Inhibiting Receptor is activated. If it is the signature of an attack, Activating Receptor is activated. Activating receptor activation results in either cytokine release or apoptosis. Here cytokine release means an alarm is generated informing the administrator and apoptosis stands for dropping of the packet. If Inhibiting Receptor is activated, it’s a normal packet there is no action taken. The technique proposed yields high accuracy, better detection rate and quick response time.
Analyzing SNOW and ZUC Security Algorithms Using NIST SP 800-22 and Enhancing their Randomness
Authors: Hassan Abdelwahab Zakaria , Elgarf Talaat A. , Zekry Abdelhalim
Published: April 2021

Confidentiality and Integrity algorithms are based on SNOW / ZUC stream cipher algorithms. These standardized algorithms are designed by the 3rd Generation Partnership Project (3GPP) for advanced mobile communication systems (4G-LTE Advanced, LTE Advanced Pro, and 5G-Next Generation).  In this paper, twenty configurations of SNOW/ZUC algorithms are studied and analyzed to select the one with the best randomness properties. Each configuration has two different S-boxes in the Finite State Machine (FSM) layer of the SNOW algorithm and Nonlinear Function (NLF) layer of the ZUC algorithm. The two S-boxes are selected from the best five S-boxes published in kinds of literature (Rijndael, Dickson, Feistel structure, New Rijndael, and Improved New Rijndael S-boxes). The NIST SP 800-22 statistical test suite involves 15 tests that are used to assess the randomness properties of each configuration. A complete simulation of each configuration SNOW/ZUC with two different S-boxes is applied using C- language. Test results showed that the best pair arrangement of S-boxes in the SNOW algorithm is the configuration (Feistel structure - Rijndael S-boxes) although the standard configuration by 3GPP is (Rijndael - Dickson S-boxes). Also, the best configuration in the ZUC algorithm is (New Rijndael - Rijndael S-boxes) although the standard configuration by 3GPP is (Feistel structure - New Rijndael S-boxes). The best configurations passed all the NIST SP 800-22 suite randomness tests successfully.
Reliability Evaluation of Repairable Parallel-Series Multi-State System Implementing Interval Valued Universal Generating Function
Authors: Renu  , Bisht Soni , Singh S. B.
Published: April 2021

In this paper, we have studied a repairable parallel-series multi-state system. The proposed system consists of m components in series and n components in parallel in which each component has three possible states. The interval universal generating function (IUGF) is presented, and the corresponding composition operators are defined. The reliability assessment of the considered system is done with the help of the IUGF approach. It is worth mentioning that IUGF got attention from various researchers due to its straightforwardness, less complexity, and universal applications. In the present model, probabilities of different components, reliability, sensitivity, and mean time to failure are evaluated with the help of the Markov process; Laplace-Steiltjes transform method applying IUGF. A numerical example has also been taken to illustrate the proposed technique.
Chirp Spreading Spectrum in Imperfect Environment and Wireless Tree Topology Network
Authors: Li Hongqiang , Zhao Dongyan , Tang Xiaoke , Gan Jie , Zhao Xu , Zhang Yubing
Published: April 2021

With the rapid development of IoT technology in recent years, higher requirements have been put forward for wireless communication technology. Low Power Wide Area Network (LPWAN) technology is emerging rapidly, the technology is characterized by low power consumption, low bandwidth, long-distance, and a large number of connections, and is specifically designed for Internet of Things applications. LoRa (Low Power Long Range Transceiver), as a typical representative of LPWAN technology, has been widely concerned and studied. This paper analyzes the performance of LoRa modulation in the tree topology network and analyzes the performance of LoRa modulation in the imperfect environment for point-to-point communication and multipoint-to-point communication. From theoretical analysis and performance simulation, it can be seen that the influence of frequency offset or multipath fading on LoRa signal is very obvious. However, when LoRa modulation is used for networking, multi-user interference will be introduced. Under the influence of many imperfect factors, the signal receiver performance of LoRa modulation will be difficult to guarantee. Because of these effects, Coordinated Multiple Points based on Timing Delay (DCoMP) is presented. Multiple nodes close to each other send the same data to the target node. Due to the inaccurate synchronization between nodes, there will be a certain relative delay when sending signals to the same target node. After the receiving node combines the signals of multiple nodes according to different relative delays, the reception performance of the signals can be improved. At the same time, the cooperative node can also actively adjust the signal sending time to improve the reception performance of the receiving node signal merging algorithm. LoRa modulation, by using DCoMP transmission, improves the reception of signals and thus the overall capacity of the system. Through the analysis of multipoint communication and single point communication, this paper is of great help to LoRa network deployment.
A General Framework of LSTM and Transfer Learning Based CFDAMA Strategy in Broadband Satellite System
Authors: He Qiang , Xiang Zheng , Ren Peng
Published: April 2021

With the development of the economy and technology, people’s requirement for communication is also increasing. Satellite networks have been paid more and more attention because of its broadband service capability and wide coverage. In this paper, we investigate the framework of a long-short term memory (LSTM) and transfer learning-based Combined Free/Demand Assignment Multiple Access (CFDAMA) scheme (CFDAMA-LSTMTL), which is a new multiple access scheme in the broadband satellite system. Generally, there is a delay time T between sending a request from the user to the satellite and receiving a reply from the satellite. So far, the traditional multiple access schemes has not processed the data traffic generated in this period of time. So, in order to transmit the data traffic in time, we propose a new prediction method, which combines LSTM with transfer learning. We introduce the prediction method into the CFDAMA scheme so that it can reduce data accumulation by the way of sending the sum slots requested by the user and the predicted request slots generated in the delay time T. A comparison with CFDAMA-PA and CFDAMA-PB is provided through simulation results, which gives the effect of the CFDAMA-LSTMTL in a broadband satellite systems.
¿Un género menor? Los sueños y el cine
Authors: Sánchez Cuervo Antolín
Published: April 2021

El cine podría equipararse a otros géneros artísticos y también a los géneros literarios, con los que la filosofía debe dialogar incluso para reencontrarse a sí misma. En este sentido, podría guardar sugerentes analogías con la experiencia del sueño, cuestión planteada por Zambrano y abordada en su día de manera explícita por el filósofo francés Edgar Morin
Investigando en animales para producir alimentos más éticos: los límites morales de la carne cultivada
Authors: Moyano Fernández Cristian
Published: April 2021

La ingente demanda global de proteínas de origen animal junto al colapso ecológico y las subsiguientes desigualdades alimentarias ha estimulado a académicos, científicos y empresarios de todo el mundo a buscar alternativas. Una de éstas es la investigación con células animales para producir carne cultivada de laboratorio. Este proceso de generación de alimentos cárnicos in vitro se presenta como una solución ante los crecientes problemas socioecológicos. Sin embargo, en este artículo se cuestionarán algunas de sus tentadoras promesas de contribuir a una mayor sostenibilidad, bienestar animal y justicia alimentaria. Más aún, se explorarán qué desafíos bioéticos plantea el polémico medio de cultivo donde se usan fetos bovinos para desarrollar este tipo de carne sintética. Desde una ética no antropocéntrica se abordarán cuatro tipos de argumentos diferentes a fin de dilucidar algunas de las limitaciones morales que conlleva esta investigación alimentaria: desde una posición deontológica, desde criterios utilitaristas, desde el enfoque de las capacidades y desde una ética de las virtudes. La suma de estos planteamientos filosóficos orientados a reflexionar sobre la carne cultivada conducirán a la conclusión de que una defensa a ultranza de este proceso es razonablemente controvertido.
Financiarización y crisis del mercado hipotecario de viviendas nuevas para los trabajadores en México
Authors: Hernández Trejo Felipe De Jesús
Published: April 2021

Este trabajo tiene por objetivo analizar la organización y transformación institucional del sector financiero hipotecario en México. Para ello se realiza un análisis sobre el número y montos de inversión y circulación, tanto de créditos hipotecarios como de Bonos Respaldados por Hipotecas (BORHs). A partir de la crisis financiera global originada en el mercado hipotecario estadounidense, paradójicamente, se ha venido fomentado el crecimiento de la propiedad hipotecaria en México a través de su financiarización. Este proceso se ha llevado a cabo mediante el incremento acelerado de la participación en el mercado de BORHs por parte de instituciones públicas de financiamiento de vivienda; en contraste con el repliegue de entidades financieras privadas e instituciones bancarias. Al incremento en la emisión de bonos y el otorgamiento de créditos hipotecarios, corresponde también un incremento en la cantidad de viviendas deshabitadas; indicio de una crisis provocada por la sobreproducción de viviendas.
La institucionalización de “convenios urbanísticos” en el marco del proceso de neoliberalización en la gestión urbana local
Authors: Peresini Natalí Del Valle
Published: April 2021

Recientemente, tanto en Argentina como en otros países de la región, se han utilizado instrumentos de gestión urbana con el fin de habilitar operaciones inmobiliarias excepcionales y recuperar parte del plusvalor del suelo urbano generado a partir de ellas. Este artículo presenta resultados de una investigación que hace foco en el proceso de institucionalización de “Convenios Urbanísticos”, instrumento destacado como fuente de financiamiento para los gobiernos locales. En el caso de la ciudad de Córdoba (Argentina), en el período 2008-2019, los resultados muestran que la institucionalización de los convenios urbanísticos legitimó la mercantilización de la potestad regulatoria, la financiarización en base al salto de renta en favor de los empresarios inmobiliarios y la concentración de los agentes que intervienen en la producción de suelo urbano.
El complejo urbano financiero inmobiliario en América latina. Introducción
Authors: López-Morales Ernesto , Gasic Klett Ivo
Published: April 2021

La crisis “subprime” de 2008 – el inicio de la “Gran Recesión” (Méndez 2018) – reveló, como nunca antes, el vínculo entre el mercado inmobiliario y las finanzas. El epicentro de la crisis fue la especulación con créditos de vivienda orientados a hogares insolventes y riesgosos, y la creación de títulos securitizados a partir de esas deudas. El concepto de “financiarización” se posicionó como tópico frecuente en los estudios urbano-regionales y en centros de investigación en finanzas. El creciente uso que se le ha dado a este concepto ha provocado cierto eclectisimo en el significado, siendo empleado indistintamente para adscribir a una tesis económica que explica descensos en la formación bruta de capital fijo y PIB en la economía, o simplemente para describir un ámbito emergente de interacción entre finanzas y – en este caso – el sector de bienes raíces. El presente dossier aborda la financiarización inmobiliaria acogiendo un abanico bastante amplio de enfoques sobre el tema. Por este motivo, se considera necesario proponer una definición genérica que vertebre los trabajos aquí expuestos. Por varias razones, conviene adoptar una perspectiva de economía política institucional, es decir vinculada al estudio de agentes e instituciones. Buscamos hablar no sólo de finanzas sino también acerca de geografía, espacios y agentes.
Temperature sensing utilizing unclad plastic optical fiber with a balloon-like bent structure
Authors: Sulaiman Nazrah Ilyana , Ngajikin Nor Hafizah , Che Abd Rashid Nurfatihah , Yaacob Afiqah , Yaacob Maslina , Ibrahim Mohd Haniff , Cholan Noran Azizan
Published: April 2021

A plastic optical fiber (POF) temperature sensor with high sensitivity is experimentally demonstrated in this work. The temperature sensor is realized by a combination of macrobending and an unclad region in the fabrication of its sensor head. The POF sensor is bent into a balloon-like structure in order to introduce the effect of macrobending. For the optimization of the sensor performance, the bending radius of the balloon-like structure is varied. Experimental results suggest that the performance is optimized when the bending radius is fixed at 55 mm. With this amount of bending radius, temperature sensitivity of up to

22.2

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1

0

−
3

∘

C

−
1

can be achieved in the range from 40°C to 80°C, with linearity of 0.99 and resolution of 0.45°C. This technique is found to improve the POF temperature sensitivity in comparison to previous developments.
Pressure measurement in gas flows using laser-induced grating lifetime
Authors: Willman Christopher , Le Page Laurent M. , Ewart Paul , Williams Benjamin A. O.
Published: April 2021

Optical diagnostics of gas-phase pressure are relatively unusual. In this work, we demonstrate a novel, rapid, and robust method to use laser-induced grating scattering (LIGS) to derive this property in real time. Previous pressure measurements with LIGS have employed a signal fitting method, but this is relatively time-consuming and requires specialist understanding. In this paper, we directly measure a decay lifetime from a LIGS signal and then employ a calibration surface constructed using a physics-based model to convert this value to pressure. This method was applied to an optically accessible single-cylinder internal combustion engine, yielding an accuracy of better than 10% at all tested conditions above atmospheric pressure. This new approach complements the existing strength of LIGS in precisely and accurately deriving temperature with a simple analysis method, by adding pressure information with a similarly simple method.
Biaxially strained germanium crossbeam with a high-quality optical cavity for on-chip laser applications
Authors: Jung Yongduck , Kim Youngmin , Burt Daniel , Joo Hyo-Jun , Kang Dong-Ho , Luo Manlin , Chen Melvina , Zhang Lin , Tan Chuan Seng , Nam Donguk
Published: April 2021

The creation of CMOS compatible light sources is an important step for the realization of electronic-photonic integrated circuits. An efficient CMOS-compatible light source is considered the final missing component towards achieving this goal. In this work, we present a novel crossbeam structure with an embedded optical cavity that allows both a relatively high and fairly uniform biaxial strain of ∼0.9% in addition to a high-quality factor of >4,000 simultaneously. The induced biaxial strain in the crossbeam structure can be conveniently tuned by varying geometrical factors that can be defined by conventional lithography. Comprehensive photoluminescence measurements and analyses confirmed that optical gain can be significantly improved via the combined effect of low temperature and high strain, which is supported by a three-fold reduction of the full width at half maximum of a cavity resonance at ∼1,940 nm. Our demonstration opens up the possibility of further improving the performance of germanium lasers by harnessing geometrically amplified biaxial strain.
Small and large scale plasmonically enhanced luminescent solar concentrator for photovoltaic applications: modelling, optimisation and sensitivity analysis
Authors: Rafiee Mehran , Chandra Subhash , Ahmed Hind , Barnham Keith , McCormack Sarah J.
Published: April 2021

Hybrid 3D Finite difference time domain-Monte Carlo ray tracing (FDTD-MCRT) algorithm has been developed to model and optimise small and large scale plasmonically-enhanced luminescent solar concentrator (pLSC) devices for photovoltaic (PV) applications. The configuration parameters (for example, dimensions, shape, and optical properties of metal nanoparticles, luminescent species, and host material) were used to characterise the probability of optical energy transfer and loss processes, as well as reflection, refraction, absorption, emission enhancement, and total internal reflection (TIR) in the pLSC. The algorithm was validated through modelling of various doping concentrations of CdSe/ZnS quantum dots (QD) and gold nano spheres (Au NS) where ∼50% enhancement in optical conversion efficiency (OCE) was observed for a plasmonic composite of 2 ppm Au NS and 0.008 wt. % QD.
Controlled single-mode emission in quantum dot micro-lasers
Authors: Zhu Si , Ma Xiang , Liu Can , Luo Wei , Liu Jia , Shi Bei , Guo Weihua , Lau Kei May
Published: April 2021

In this paper, we demonstrate an efficient and easy fabrication method for whispering-gallery-mode (WGM) manipulation and report the first electrically driven single-mode quantum dot micro-ring (QDMR) lasers. Using self-assembled InAs/InAlGaAs QD active layers with deeply etched azimuthal gratings, continuous-wave (CW) lasing with controllable single-mode emission wavelengths covering 1300 nm to 1370 nm has been achieved. A record-high side-mode-suppression-ratio (SMSR) value of 49 dB is obtained. These QDMR lasers exhibit excellent single-mode lasing stabilities over the current and temperature tuning range with a thermal tunability of 0.092 nm/°C. The concept is applicable to other wavelength bands depending on the gain spectrum, demonstrating a feasible solution in realizing energy-efficient and densely integrated photonic building blocks.
Switchable generation of azimuthally- and radially-polarized terahertz beams from a spintronic terahertz emitter
Authors: Niwa Hiroaki , Yoshikawa Naotaka , Kawaguchi Masashi , Hayashi Masamitsu , Shimano Ryo
Published: April 2021

We propose and demonstrate a method of generating two fundamental terahertz cylindrical vector beams (THz-CVBs), namely the azimuthally- and radially-polarized THz pulses, from a spintronic THz emitter. We begin by presenting that the spintronic emitter generates the HE21 mode, a quadrupole like polarization distribution, when placed between two magnets with opposing polarity. By providing an appropriate mode conversion using a triangular Si prism, we show both from experiment and numerical calculation that we obtain azimuthal and radial THz vector beams. The proposed method facilitates the access of CVBs and paves the way toward sophisticated polarization control in the THz regime.
Ranging and velocimetry measurements by phase-based MTCW lidar
Authors: Bayer Mustafa Mert , Boyraz Ozdal
Published: April 2021

We propose a complementary phase detection algorithm to enhance the capabilities of the multi-tone continuous wave (MTCW) lidar for single-shot simultaneous ranging and velocimetry measurements. We show that the phase of the Doppler-shifted RF tones and the amount of the induced Doppler frequency shift can be used to extract the phase and velocity information, simultaneously. A numerical case study and experimental work have been performed for the proof of concept. We show that the velocity resolutions are limited by frequency resolution and the ranging resolution is determined by the temporal resolution. Experimentally, we obtain 8.08 ± 0.8cm/s velocity measurement and 111.9cm range measurements with ±0.75cm resolution in a 6-tone MTCW lidar system.
Experimental demonstration of topological slow light waveguides in valley photonic crystals
Authors: Yoshimi Hironobu , Yamaguchi Takuto , Katsumi Ryota , Ota Yasutomo , Arakawa Yasuhiko , Iwamoto Satoshi
Published: April 2021

We experimentally demonstrate topological slow light waveguides in valley photonic crystals (VPhCs). We employed a bearded interface formed between two topologically-distinct VPhCs patterned in an air-bridged silicon slab. The interface supports both topological and non-topological slow light modes below the light line. By means of optical microscopy, we observed light propagation in the topological mode in the slow light regime with a group index

n

g

over 30. Furthermore, we confirmed light transmission via the slow light mode even under the presence of sharp waveguide bends. In comparison between the topological and non-topological modes, we found that the topological mode exhibits much more efficient waveguiding than the trivial one, demonstrating topological protection in the slow light regime. This work paves the way for exploring topological slow-light devices compatible with existing photonics technologies.
Electro-optically tunable microring laser monolithically integrated on lithium niobate on insulator
Authors: Yin DiFeng , Zhou Yuan , Liu Zhaoxiang , Wang Zhe , Zhang Haisu , Fang Zhiwei , Chu Wei , Wu Rongbo , Zhang Jianhao , Chen Wei , Wang Min , Cheng Ya
Published: April 2021

We demonstrate monolithic integration of an electro-optically (EO) tunable microring laser on lithium niobate on insulator (LNOI) platform. The device is fabricated by photolithography assisted chemo-mechanical etching, and the pump laser is evanescently coupled into the erbium (

E

r

3
+

)-doped lithium niobate (LN) microring laser using an undoped LN waveguide mounted above the microring. The quality factor of the LN microring resonator is measured as high as

1.54

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0

5

at the wavelength of 1542 nm. Lasing action can be observed at a pump power threshold below 3.5 mW using a 980 nm continuous-wave pump laser. Finally, tuning of the laser wavelength is achieved by varying the electric voltage on the microelectrodes fabricated in the vicinity of a microring waveguide, showing an EO coefficient of 0.33 pm/V.
Low loss ridge-waveguide grating couplers in lithium niobate on insulator
Authors: Yang Sipan , Li Yaqian , Xu Jinbin , Wang Min , Wu Liying , Quan Xueling , Liu Min , Fu Liucheng , Cheng Xiulan
Published: April 2021

The conventional ridge waveguides and grating-couplers in x-cut single-crystal lithium niobate on insulator (LNOI), have been designed, fabricated and characterized. All the device structures patterned on the sample were monolithically defined by one step of the electron-beam lithography process, followed by dry-etching. A low insertion loss (IL) of −6.3 dB/coupler for transverse-electric (TE) polarization inputs at the wavelength of 1543 nm was measured in the fabricated best device with the tapered structures, and exhibited a broad 3-dB optical bandwidth of more than 90 nm. This work may pave the way towards the future research of high-efficiency photonic waveguide components in thin-film LNOI.
Imputation of spatially-resolved transcriptomes by graph-regularized tensor completion
Authors: Li Zhuliu , Song Tianci , Yong Jeongsik , Kuang Rui
Published: April 2021

High-throughput spatial-transcriptomics RNA sequencing (sptRNA-seq) based on in-situ capturing technologies has recently been developed to spatially resolve transcriptome-wide mRNA expressions mapped to the captured locations in a tissue sample. Due to the low RNA capture efficiency by in-situ capturing and the complication of tissue section preparation, sptRNA-seq data often only provides an incomplete profiling of the gene expressions over the spatial regions of the tissue. In this paper, we introduce a graph-regularized tensor completion model for imputing the missing mRNA expressions in sptRNA-seq data, namely FIST, Fast Imputation of Spatially-resolved transcriptomes by graph-regularized Tensor completion. We first model sptRNA-seq data as a 3-way sparse tensor in genes (p-mode) and the (x,y) spatial coordinates (x-mode andy-mode) of the observed gene expressions, and then consider the imputation of the unobserved entries or fibers as a tensor completion problem in Canonical Polyadic Decomposition (CPD) form. To improve the imputation of highly sparse sptRNA-seq data, we also introduce a protein-protein interaction network to add prior knowledge of gene functions, and a spatial graph to capture the the spatial relations among the capture spots. The tensor completion model is then regularized by a Cartesian product graph of protein-protein interaction network and the spatial graph to capture the high-order relations in the tensor. In the experiments, FIST was tested on ten 10x Genomics Visium spatial transcriptomic datasets of different tissue sections with cross-validation among the known entries in the imputation. FIST significantly outperformed the state-of-the-art methods for single-cell RNAseq data imputation. We also demonstrate that both the spatial graph and PPI network play an important role in improving the imputation. In a case study, we further analyzed the gene clusters obtained from the imputed gene expressions to show that the imputations by FIST indeed capture the spatial characteristics in the gene expressions and reveal functions that are highly relevant to three different kinds of tissues in mouse kidney.
Avoiding the bullies: The resilience of cooperation among unequals
Authors: Foley Michael , Smead Rory , Forber Patrick , Riedl Christoph
Published: April 2021

Can egalitarian norms or conventions survive the presence of dominant individuals who are ensured of victory in conflicts? We investigate the interaction of power asymmetry and partner choice in games of conflict over a contested resource. Previous models of cooperation do not include both power inequality and partner choice. Furthermore, models that do include power inequalities assume a static game where a bully’s advantage does not change. They have therefore not attempted to model complex and realistic properties of social interaction. Here, we introduce three models to study the emergence and resilience of cooperation among unequals when interaction is random, when individuals can choose their partners, and where power asymmetries dynamically depend on accumulated payoffs. We find that the ability to avoid bullies with higher competitive ability afforded by partner choice mostly restores cooperative conventions and that the competitive hierarchy never forms. Partner choice counteracts the hyper dominance of bullies who are isolated in the network and eliminates the need for others to coordinate in a coalition. When competitive ability dynamically depends on cumulative payoffs, complex cycles of coupled network-strategy-rank changes emerge. Effective collaborators gain popularity (and thus power), adopt aggressive behavior, get isolated, and ultimately lose power. Neither the network nor behavior converge to a stable equilibrium. Despite the instability of power dynamics, the cooperative convention in the population remains stable overall and long-term inequality is completely eliminated. The interaction between partner choice and dynamic power asymmetry is crucial for these results: without partner choice, bullies cannot be isolated, and without dynamic power asymmetry, bullies do not lose their power even when isolated. We analytically identify a single critical point that marks a phase transition in all three iterations of our models. This critical point is where the first individual breaks from the convention and cycles start to emerge.
Quantifying evolutionary importance of protein sites: A Tale of two measures
Authors: Sharir-Ivry Avital , Xia Yu
Published: April 2021

A key challenge in evolutionary biology is the accurate quantification of selective pressure on proteins and other biological macromolecules at single-site resolution. The evolutionary importance of a protein site under purifying selection is typically measured by the degree of conservation of the protein site itself. A possible alternative measure is the strength of the site-induced conservation gradient in the rest of the protein structure. However, the quantitative relationship between these two measures remains unknown. Here, we show that despite major differences, there is a strong linear relationship between the two measures such that more conserved protein sites also induce stronger conservation gradient in the rest of the protein. This linear relationship is universal as it holds for different types of proteins and functional sites in proteins. Our results show that the strong selective pressure acting on the functional site in general percolates through the rest of the protein via residue-residue contacts. Surprisingly however, catalytic sites in enzymes are the principal exception to this rule. Catalytic sites induce significantly stronger conservation gradients in the rest of the protein than expected from the degree of conservation of the site alone. The unique requirement for the active site to selectively stabilize the transition state of the catalyzed chemical reaction imposes additional selective constraints on the rest of the enzyme.
Ionotropic Receptor-dependent cool cells control the transition of temperature preference in Drosophila larvae
Authors: Tyrrell Jordan J. , Wilbourne Jackson T. , Omelchenko Alisa A. , Yoon Jin , Ni Lina
Published: April 2021

Temperature sensation guides animals to avoid temperature extremes and to seek their optimal temperatures. The larval stage of Drosophila development has a dramatic effect on temperature preference. While early-stage Drosophila larvae pursue a warm temperature, late-stage larvae seek a significantly lower temperature. Previous studies suggest that this transition depends on multiple rhodopsins at the late larval stage. Here, we show that early-stage larvae, in which dorsal organ cool cells (DOCCs) are functionally blocked, exhibit similar cool preference to that of wild type late-stage larvae. The molecular thermoreceptors in DOCCs are formed by three members of the Ionotropic Receptor (IR) family, IR21a, IR93a, and IR25a. Early-stage larvae of each Ir mutant pursue a cool temperature, similar to that of wild type late-stage larvae. At the late larval stage, DOCCs express decreased IR proteins and exhibit reduced cool responses. Importantly, late-stage larvae that overexpress IR21a, IR93a, and IR25a in DOCCs exhibit similar warm preference to that of wild type early-stage larvae. These data suggest that IR21a, IR93a, and IR25a in DOCCs navigate early-stage larvae to avoid cool temperatures and the reduction of these IR proteins in DOCCs results in animals remaining in cool regions during the late larval stage. Together with previous studies, we conclude that multiple temperature-sensing systems are regulated for the transition of temperature preference in fruit fly larvae.
A comparison of 71 binary similarity coefficients: The effect of base rates
Authors: Brusco Michael , Cradit J. Dennis , Steinley Douglas
Published: April 2021

There are many psychological applications that require collapsing the information in a two-mode (e.g., respondents-by-attributes) binary matrix into a one-mode (e.g., attributes-by-attributes) similarity matrix. This process requires the selection of a measure of similarity between binary attributes. A vast number of binary similarity coefficients have been proposed in fields such as biology, geology, and ecology. Although previous studies have reported cluster analyses of binary similarity coefficients, there has been little exploration of how cluster memberships are affected by the base rates (percentage of ones) for the binary attributes. We conducted a simulation experiment that compared two-cluster K-median partitions of 71 binary similarity coefficients based on their pairwise correlations obtained under 15 different base-rate configurations. The results reveal that some subsets of coefficients consistently group together regardless of the base rates. However, there are other subsets of coefficients that group together for some base rates, but not for others.
Applications of teledentistry in a French inmate population: A one-year observational study
Authors: Inquimbert Camille , Balacianu Ioan , Huyghe Nicolas , Pasdeloup Joao , Tramini Paul , Meroueh Fadi , Montal Sylvie , Bencharit Sompop , Giraudeau Nicolas
Published: April 2021

Teledentistry oral examination protocol was evaluated for one year at the Villeneuve-lès-Maguelone Correctional Facility. The aim of the study was to simplify the obligatory dental consultation protocol at the entrance visit for new detainees. 1051 detainees were enrolled and 651 of them (58.9%) accepted an oral examination by teledentistry throughout the entire year of 2018. Only 1 inmate did not need treatment and 88.06% of those who have been examined had at least one untreated cavitated carious lesion. Forty-four percent of people who received a teledentistry check-up were referred to a dentist with a dental emergency. The use of teledentistry at the entry visit in a detention facility may facilitate the oral health screening without wasting the dentist’s time, and may allow an optimization of the inmate’s oral healthcare.
Ultrasound-guided fine needle aspiration cytology and ultrasound examination of thyroid nodules in the UAE: A comparison
Authors: Al-Salam Suhail , Sharma Charu , Abu Sa’a Maysam T. , Afandi Bachar , Aldahmani Khaled M. , Al Dhaheri Alia , Yahya Hayat , Al Naqbi Duha , Al Zuraiqi Esraa , Mohamed Baraa Kamal , Almansoori Shamsa Ahmed , Al Zaabi Meera , Al Derei Aysha , Al Shamsi Amal , Kaabi Juma Al
Published: April 2021

Background

Thyroid nodules are a common clinical finding and most are benign, however, 5–15% can be malignant. There is limited regional data describing the accuracy of ultrasound-guided fine needle aspiration (FNA) cytological examination compared to ultrasound examination of thyroid in patients who have undergone thyroid surgery.

Methods

A retrospective analysis of ultrasonographic (US) reports, FNA cytology reports and histopathology reports of 161 thyroid nodules presented at the endocrine center at Tawam hospital in Al Ain city, the United Arab Emirates during the period 2011–2019 was performed. US reports and images with FNA cytopathology reports and slides were reviewed by an independent radiologist and pathologist.

Results

In total, 40 nodules were reported as benign by US examination, while very low suspicious, low suspicious, intermediate suspicious and highly suspicious categories were reported in 21, 41, 14 and 45 nodules respectively. In addition, 68 nodules were reported as benign (Bethesda category II), while atypical follicular cells of unknown significance (Bethesda category III), follicular neoplasm (Bethesda category IV), suspicious for malignancy (Bethesda category V), and malignant (Bethesda category VI) categories were reported in 33, 9, 24 and 27 nodules respectively. The risk of malignancy for US benign nodules was 5%, while the risks of malignancy in very low suspicious, low suspicious, intermediate suspicious and highly suspicious nodules were 52%, 36%, 100% and 87%, respectively. The risk of malignancy for Bethesda category II was 3%, while the risks of malignancy in category III, IV, V and VI were 58%, 67%, 96% and 100%, respectively.

Conclusion

Thyroid FNA cytological examination and ultrasonography are key tools in predicting malignancy in thyroid nodules. Thyroid nodules with the diagnosis of Bethesda category III & IV run a high risk of malignancy thus more vigilance is required.
The pulmonary mycobiome—A study of subjects with and without chronic obstructive pulmonary disease
Authors: Martinsen Einar M. H. , Eagan Tomas M. L. , Leiten Elise O. , Haaland Ingvild , Husebø Gunnar R. , Knudsen Kristel S. , Drengenes Christine , Sanseverino Walter , Paytuví-Gallart Andreu , Nielsen Rune
Published: April 2021

Background

The fungal part of the pulmonary microbiome (mycobiome) is understudied. We report the composition of the oral and pulmonary mycobiome in participants with COPD compared to controls in a large-scale single-centre bronchoscopy study (MicroCOPD).

Methods

Oral wash and bronchoalveolar lavage (BAL) was collected from 93 participants with COPD and 100 controls. Fungal DNA was extracted before sequencing of the internal transcribed spacer 1 (ITS1) region of the fungal ribosomal RNA gene cluster. Taxonomic barplots were generated, and we compared taxonomic composition, Shannon index, and beta diversity between study groups, and by use of inhaled steroids.

Results

The oral and pulmonary mycobiomes from controls and participants with COPD were dominated by Candida, and there were more Candida in oral samples compared to BAL for both study groups. Malassezia and Sarocladium were also frequently found in pulmonary samples. No consistent differences were found between study groups in terms of differential abundance/distribution. Alpha and beta diversity did not differ between study groups in pulmonary samples, but beta diversity varied with sample type. The mycobiomes did not seem to be affected by use of inhaled steroids.

Conclusion

Oral and pulmonary samples differed in taxonomic composition and diversity, possibly indicating the existence of a pulmonary mycobiome.
Matrix Metalloproteinase-9 (MMP-9) induced disruption of intestinal epithelial tight junction barrier is mediated by NF-κB activation
Authors: Al-Sadi Rana , Engers Jessica , Haque Mohammad , King Steven , Al-Omari Deemah , Ma Thomas Y.
Published: April 2021

Background

Matrix Metalloproteinase-9 (MMP-9) has been shown to play a key role in mediating inflammation and tissue damage in inflammatory bowel disease (IBD). In patients with IBD, the intestinal tight junction (TJ) barrier is compromised as characterized by an increase in intestinal permeability. MMP-9 is elevated in intestinal tissue, serum and stool of patients with IBD. Previous studies from our laboratory showed that MMP-9 causes an increase in intestinal epithelial TJ permeability and that the MMP-9 induced increase in intestinal permeability is an important pathogenic factor contributing to the development of intestinal inflammation in IBD. However, the intracellular mechanisms that mediate the MMP-9 modulation of intestinal barrier function remain unclear.

Aims

The main aim of this study was to further elucidate the molecular mechanisms involved in MMP-9 induced increase in intestinal epithelial TJ permeability using Caco-2 monolayers as an in-vitro model system.

Results

MMP-9 induced increase in Caco-2 TJ permeability was associated with activation and cytoplasmic-to-nuclear translocation of NF-κB p65. Knocking-down NF-κB p65 by siRNA transfection prevented the MMP-9 induced expression of the NF-κB target gene IL-8, myosin light chain kinase (MLCK) protein expression, and subsequently prevented the increase in Caco-2 TJ permeability. In addition, the effect of MMP-9 on Caco-2 intestinal epithelial TJ barrier function was not mediated by apoptosis or necrosis.

Conclusion

Our data show that the MMP-9 induced disruption of Caco-2 intestinal epithelial TJ barrier function is regulated by NF-κB pathway activation of MLCK.