bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Koopman operator theory to the control of nonlinear bubble dynamics
Authors: Gibson Andrew J. , Yee Xin C. , Calvisi Michael L.
Published: May 2022

Microbubbles are widely used in biomedicine for ultrasound contrast imaging and are a promising vehicle for targeted drug and gene delivery. The ability to control the oscillations of bubbles through the applied ultrasound can improve the effectiveness of these treatments, for example, by enhancing the acoustic echo or inciting bubble rupture at precise locations. Koopman operator theory has gained interest in the past decade as a framework for rigorously transforming nonlinear dynamics on the state space into linear dynamics on abstract function spaces, which preserves the underlying nonlinear dynamics of the system. These spaces can be approximated purely through machine learning and data-driven methodologies, which then enables the application of classical linear control strategies to strongly nonlinear systems. Here, we use a Koopman linear quadratic regulator (LQR) to control the nonlinear dynamics of spherical bubbles, as described by the well-known Rayleigh-Plesset equation, with two novel objectives: (1) stabilization of the bubble at a nonequilibrium radius and (2) simple harmonic oscillation at amplitudes large enough to incite nonlinearities. Control is implemented through both broadband and single-frequency transducers that are modulated by the Koopman LQR controller. We repeat these results using Koopman model predictive control (MPC), which allows for the implementation of constraints. This work is a step towards controlling nonspherical shape modes of encapsulated microbubbles.
Mechanistic analysis of B-line formation in lung ultrasound
Authors: Thomas Gilles P. , Sapozhnikov Oleg A. , Maxwell Adam , Thiel Jeff , Cunitz Bryan W. , Bailey Michael R. , Steinbock Kyle , Anderson Layla , Kessler Ross , Adedipe Adeyinka , Khokhlova Tatiana D.
Published: May 2022

The number and distribution of lung ultrasound (LUS) imaging artifacts—B-lines—is correlated with the presence of lung interstitial syndrome such as viral infection and pulmonary edema. The detection and quantification of B-lines is machine and operator dependent, and the mechanisms for B-line formation are not fully understood. The goals of this work were to collect RF data during LUS exams in patients with pulmonary edema and to compare to the signals and corresponding images simulated numerically to elucidate the B-line formation process. Verasonics ultrasound engine (VUE) with a phased array probe (4.5 MHz) was used to perform standard 10-zone LUS in ten patients with confirmed pulmonary edema. The RF data corresponding to each B-mode image and a series of 35 plane wave acquisitions were collected for off-line analyses. Finite element modeling of LUS pulse propagation was performed in COMSOL with fluid-filled inclusions of variable sizes and shapes in air-like medium simulating edematous lung areas. The B-mode image resulting from the simulated RF signals was reconstructed using VUE beamforming. The B-lines similar to those observed experimentally formed in simulated images only under specific conditions of sizes and shapes of water-filled areas relatively to LUS imaging wavelength. [Work supported by NIH R01EB023910.]
Enhancing graduate, undergraduate, and vocational school education with research and development internships and capstone projects
Authors: Brown David A.
Published: May 2022

The Center for Innovation and Entrepreneurship (CIE) and Advanced Technology and Manufacturing Center (ATMC) of UMass Dartmouth provides a facility for collaboration with industry. Local businesses provide internships, research opportunities, and specialized training in acoustics that enhance student growth and practical learning. The College of Engineering benefits from the industrial sponsorship for undergraduate capstone projects as well as graduate research. Students benefit from practical training and earning money for tuition and potential post-graduation employment. This tradition has grown over decades with the maturation of facilities for advancement in engineering and underwater acoustics. This presentation will present some student focused success stories within the area of engineering acoustics and transduction.
On the 50th anniversary of ASTM E33, a history of ASTM International standards on building and environmental acoustics
Authors: Stewart Noral D. , Wolfram Eric P. , Peppin Richard J. , Putnam Robert
Published: May 2022

This year marks the 50th anniversary of ASTM International Committee E33 on Building and Environmental Acoustics which combined all ASTM activity in these areas into one committee, though work on ASTM standards for measurement of sound absorption and transmission had started prior to 1950. This presentation will discuss the history of the committee and ASTM International standards in acoustics including the leadership that has made it possible.
Revision of a common product noise measurement standard in response to user concerns
Authors: Hellweg Robert D. , Lind Stephen J.
Published: May 2022

Many manufacturers of products and equipment use ISO 3744 to measure and report their sound power levels. (ISO 3744 is nationally adopted as an American standard—ANSI/ASA S12.54.) The products include almost all sources that are primarily stationary such as household appliances, computers, heavy machinery, and construction equipment. The standard is referenced in European regulations and hundreds of machine-specific standards. Many users of ISO 3744 have complained that it was too complicated, complex, and difficult to use. In response to these user concerns, the ISO working group responsible (ISO TC43/SC1/WG28) is revising ISO 3744 to make it simpler to use and less complex. Among the many changes, the draft standard includes the following: removing rarely used conditions and reducing the complexity of background noise calculations. The revision also removes certain aspects and places them into two new standards also under development: (1) qualification of measurement rooms ISO 26102-1 and (2) measurement uncertainty ISO 5114-1. Draft standards are being balloted in member countries of ISO TC43/SC1 (Noise). This paper will describe the provisions in the draft revision of each of these three noise standards and their current status.
Generation and steering of airborne acoustic vortices with broadband electro-active spiral gratings
Authors: Ealo Joao , Muelas-Hurtado Ruben , Volke-Sepúlveda Karen
Published: May 2022

Acoustic beam shaping technology has flourished in the last decade, motivated by its important applications. For example, in the context of contactless manipulation, the use of structured ultrasonic fields has led to significant advances, such as the development of the acoustic tweezers based on the use of ultrasonic vortex beams. In this work, we present a powerful and efficient technique to structure acoustic fields based on the use of planar electro-active diffraction gratings, which can be tailored in practically arbitrary shapes. For this purpose, a lower electrode with the desired shape is printed on a circuit board and covered with an active ferroelectret film, whose metallized top surface acts as a continuous upper electrode. Importantly, these devices can be operated within a broad spectral range of ultrasonic frequencies. Two kinds of structured fields are demonstrated: a focused acoustic vortex and the simultaneous generation of multiple acoustic Bessel beams of different topological charges, well separated among each other along the propagation axis. In both cases, the main parameters of the field can be finely and continuously tuned by setting the operation frequency, which allows an axial steering of the vortices. Experimental results exhibit very good agreement with theoretical analysis and numerical simulations.
Physiological studies of timbre encoding in the auditory midbrain
Authors: Fritzinger Johanna B. , Carney Laurel H.
Published: May 2022

Perceived timbre, especially brightness, is influenced by the spectral peaks of sounds. We hypothesize that spectral peaks are reliably encoded in the inferior colliculus (IC) due to capture and off-characteristic frequency (CF) inhibition. Capture occurs when a component near CF saturates the inner-hair-cell response, reducing the amplitude of neural fluctuations, the low-frequency changes in auditory-nerve firing rate that arise from the interaction of components within complex sounds. IC neurons are sensitive to amplitude modulation and respond to neural fluctuations with enhanced or suppressed rates. Extracellular single-unit recordings were made in the IC of awake rabbits in response to synthetic harmonic stimuli with triangular-shaped spectral magnitudes and zero-phase. Stimuli were presented at 40–80 dB SPL to test for robust encoding over a range of suprathreshold levels. Responses were compared to the output of an auditory-nerve model that exhibits capture followed by a modulation-tuned midbrain model. Results were generally consistent with model predictions, especially for cells suppressed by modulations. Dependent on the modulation transfer function type, responses show dips or peaks in average rate over many levels when the peak harmonic frequency matches CF. This work fills a gap in neural timbre research by investigating spectral peak encoding in the auditory midbrain.
Perception of temporal cues in word segments as a function of spectral resolution and stimulus context
Authors: Brown Hannah , Song Viv , Low Michelle , Xie Zilong
Published: May 2022

Auditory temporal processing is affected by the spectral resolution of the target stimuli (e.g., processed via a cochlear implant) and the surrounding stimulus context. This study examined how spectral resolution interacts with stimulus context to influence the perception of temporal cues in word segments. Normal-hearing adults performed categorization tasks on unprocessed and 8-channel vocoded versions of a Buy-Pie word contrast with varying voice-onset time (VOT). Besides being presented in isolation, the target words were preceded by a sentence or sentence-envelope-modulated or unmodulated speech-shaped noises. The carrier stimuli were presented ipsilaterally or contralaterally to the target words. Preliminarily results (N = 7) showed that participants tended to report more “Buy” responses in conditions with carrier stimuli than in isolation, particularly for words with longer VOTs. The context effect appears to be largely unchanged between unprocessed and vocoded words. The context effect was significantly reduced for the contralateral presentation of the carrier stimuli than the ipsilateral presentation. These results suggest that stimulus context may affect auditory temporal processing independent of spectral resolution, and the context effect appears to be primarily governed by peripheral processing. Such context effect might present some challenges for cochlear-implants users to perceive connected speech in real-life situations.
Characterizing an auditory symptom subtype of concussion
Authors: Koerner Tess K. , Papesh Melissa A. , Theodoroff Sarah M. , Dean Nicole , Kampel Sean D. , Wilhelm Jennifer , Rockwood Ryan , Chesnutt James , Gallun Frederick J.
Published: May 2022

Anecdotal clinical reports and recent research findings suggest that auditory symptoms are common following a mild traumatic brain injury (mTBI). Typically, only tinnitus is captured on a case history. Self-reported noise sensitivity/hyperacusis and difficulty with speech are not commonly included in the assessment of mTBI symptoms. The present study completed a Principal Component Analysis on responses to three commonly administered hearing health questionnaires from 95 normal-hearing Veterans and non-Veterans with and without history of mTBI. Results allowed for the identification of self-report items reflective of auditory symptoms in individuals with mTBI. These results were combined with expert opinion to develop eight auditory symptom rating-scale items that were added to a new mTBI symptom questionnaire, the Concussion Symptom Subtype Inventory (CSSI). Data collection using the CSSI is ongoing at the Oregon Health and Science University Concussion Clinic. The development of the auditory items and current data from the CSSI will be discussed. This work will provide important information about auditory symptoms in this patient population and will help drive future research that aims to better understand and measure the effects of mTBI on auditory processing. Future work will aim to assess the validity of the CSSI for clinically assessing mTBI symptoms.
Elastic bilayer phononic crystal
Authors: Deng Yuanchen , Oudich Mourad , Jing Yun
Published: May 2022

Inspired by twisted bilayer graphene, we present an elastic bilayer consisting of a plate with two honeycomb lattices of mechanical resonators on both sides of the plate. Surface acoustic waves (SAW), which can interact depending on the thickness of the plate, are supported by each side of the plate. Beyond twisting a lattice with respect to the other, the coupling strengths between the two sides can be controlled via the plate thickness, which strongly affects the dispersion of elastic waves in the bilayer structure. The dispersion relationship of the SAW is theoretically characterized by calculating the band structure for the cases of AA and AB stacking configurations, as well as for special cases of twisting angles that produce sublattices with even and odd symmetries. Furthermore, we explore the topological characteristics of the bands and uncover a possible mechanism of creating topological elastic Valley states. The proposed bilayer plate could constitute a promising platform for manipulating mechanical waves and exploring quantum analog phenomena which could open routes toward innovative mechanical and optomechanical devices at the microscale, for instance.
Machine learning non-reciprocity of a passive linear waveguide with a local nonlinear, asymmetric gate
Authors: Wang Chongan , Mojahed Alireza , Tawfick Sameh , Vakakis Alexander F.
Published: May 2022

In this work, we propose a new, simple, and highly effective passive phononic waveguide with controllable global non-reciprocity by means of local nonlinear and asymmetric elements. The nonlinearity and asymmetry in the waveguide are realized by means of a local nonlinear gate with a cubic stiffness nonlinearity that couples two detuned, dissipative gate oscillators. A wave transmits across the nonlinear gate by applying a harmonic excitation. The transmitted wave is either monochromatic or strongly modulated (SMR) and triggers the global non-reciprocity. The objectives of this work are to study the effect of local nonlinearity and asymmetry on the global non-reciprocal acoustics and to optimize the non-reciprocal performance of the waveguide. We employ the complexification averaging method (CX-A) in the acoustics to predict the bifurcations that govern the non-reciprocal acoustics. However, a limitation of the single-frequency CX-A method is its failure to predict the SMRs. Alternatively, we train machine learning simulators in order to optimize the two performance measures, i.e., energy transmissibility and non-reciprocity. The trained machine learning model drastically saves the simulation time and allows the optimization of performances. Our results show how powerful machine learning approaches can be employed for designing and optimizing practical waveguides with tailored non-reciprocity features.
Acoustical testing of face coverings using an artificial acoustic head with speech audio
Authors: Ruhala Laura , Ruhala Richard J. , Hernandez-Borjas Danny
Published: May 2022

The COVID-19 pandemic has caused many communities to require or at least recommend the wearing of face coverings, masks, and/or shields inside indoor public spaces to reduce the transmission rate of the virus. Several types of face coverings are studied, including standardized N95 and KN95, assorted cloth, and clear plastic face shields. They are evaluated on an acoustical head and torso simulator (HATS) setup in a classroom with two different locations for monitoring via a sound level meter. The HATS is used as a controlled and repeatable artificial voice or sound source, which reproduces the ITU-T artificial speech signals as well as playback of real speech signals for American English, male and female voices. The signals are recorded with a sound level meter at a distance of 2 and 6 m between source and receiver in a classroom environment. These signals evaluated in time and frequency domains to better understand the acoustical difference between the no-mask and various masks conditions. These are compared with the same classroom environment but using white noise test signals.
Vocal aesthetics—Theoretical and methodological considerations
Authors: Sorokowski Piotr , Luty Jerzy , Groyecka-Bernard Agata , Pisanski Katarzyna
Published: May 2022

Research on the influence of human voice on perceived attractiveness and other characteristics has a long tradition in psychology, aesthetics, and neuro-cognitive science. Here, we would like to present the perspectives, methodologies and goals of voice studies within these disciplines. Then, we will focus on the most common voice studies in psychology (i.e., evaluation of different characteristics based on the voice samples). Hundreds of studies have measured properties of the human voice to understand what vocal features tell about the speakers and how they influence their social perception. However, there is surprisingly little consensus about their methodology, specifically in terms of the verbal content and duration of voice recordings (i.e., speech stimulus types). While in some studies researchers record only vowel sounds or single words, others use sentences, longer, scripted statements or fragments of spontaneous conversations. The duration and verbal content of voice recordings could affect key nonverbal properties of speech, and therefore, in our project, we assessed the effect of speech stimulus type on voice perception in playback experiments. In our presentation, will describe the results of our previous studies and based on these we will also present our recommendations on future psychological experiments. [Work supported by NCN 2016/23/B/HS6/00771]
Comparison of one-dimensional and three-dimensional glottal flow models in left-right asymmetric vocal fold conditions
Authors: Yoshinaga Tsukasa , Zhang Zhaoyan , Iida Akiyoshi
Published: May 2022

While the glottal flow is often simplified as one-dimensional (1D) in computational models of phonation to reduce computational costs, the 1D flow model has not been validated in left-right asymmetric vocal fold conditions, as often occur in both normal and pathological voice production. It is unclear to what extent the 1D model approximates the effect of three-dimensional (3D) flow phenomena and fluid-structure interaction. In this study, we performed 1D and 3D flow simulations coupled with the two-mass vocal fold model and compared vocal fold vibration patterns at different degrees of left-right stiffness asymmetry. The flow and acoustic fields in 3D were predicted by solving the compressible Navier-Stokes equations using the volume penalization method and considering the moving vocal fold wall as an immersed boundary. The results showed that vocal fold vibration amplitudes and left-right phase differences in the 3D flow were predicted by the 1D flow model under conditions of small left-right asymmetry, while vocal fold vibration amplitudes were underestimated at conditions of large left-right asymmetry. This indicates that 1D flow models may be sufficient in modeling phonation under left-right asymmetric conditions, although the performance can be further improved by more accurately predicting air pressure on vocal fold surface.
Shallow water acoustic spatial coherence
Authors: Kamal Ashley , Miller Madeline
Published: May 2022

The understanding and ability to predict acoustic spatial coherence in dynamic ocean environments is limited, as it depends on many small scale physical processes. Development and validation of theoretical models requires the assessment of coherence in diverse ocean conditions. We compute spatial coherence measures for the SwellEx-96 experiment and evaluate the functional dependence of coherence on frequency in a shallow water environment. The acoustic signals are low-frequency multi-tones (50–400 Hz) transmitted from a ship-towed source and received on horizontal bottom-mounted arrays deployed across the 240-260m isobaths. Following the approach developed by Heaney (2011), coherence measures employed are the “power factor” and “eigenvalue ratio” of the eigenvalues of a cross-spectral density matrix. Advantageously, these methods account for both amplitude and phase, do not require a signal model, and were shown to have low sensitivity to array element position error. We assess whether spatial coherence calculated from the SwellEx-96 data is functionally related to frequency and determine the effect of range on the spatial coherence estimate. Results from this analysis are compared to existing coherence length data estimates and theoretical models.
Ocean acoustic boundary characterization multi-national experiments
Authors: Holland Charles W. , Nielsen Peter
Published: May 2022

The condition of the sea surface and seabed boundaries of the ocean often significantly affect the characteristics of acoustic signal propagation, reverberation and noise particularly in shallow water. A series of collaborative experiments were conducted from 2000 to 2009 to better understand the impact of ocean boundary characteristics on ocean acoustic signals in the frequency range of 100 – 5000 Hz. Acoustic measurements included long-range (waveguide) propagation, reverberation, and clutter as well as measurements of local boundary reflection and scattering. These were supported by oceanographic, geophysical and geologic measurements. Experimental locations included the Tyrrhenian Sea, Straits of Sicily, the New Jersey shelf, and the Scotian shelf with collaborators from NATO-STO CMRE and national laboratories and institutions from Italy, Canada, France, and the US. This talk will provide an overview of some of the main results from these experiments. [Research sponsored by CMRE(NATO), ONR(US), NUWC(US), INGV(IT), SHOM(FR), DRDC(CA), Italian Navy(IT).]
Acoustical properties of granular aerogel agglomerates
Authors: Dasyam Amrutha , Xue Yutong , Sharma Bhisham , Bolton J. S.
Published: May 2022

Granular aerogel agglomerates obtain their unique mechanical and functional properties from their underlying mesoporous structure and intergranular interactions. In this presentation, we focus on the acoustical properties of granular aerogel layers and present experimental results characterizing the absorption behavior of granular silica aerogels with average particle sizes ranging from 5 μm to 2 mm. Our results show that the absorption behavior of granular aerogels strongly depends on the average particle size. To better understand this particle size dependence, we model the granular agglomerates using Biot’s limp and poro-elastic formulation. Finally, we use the developed model to design layered aerogel granular stacks with wideband sound absorption properties.
Railway noise and long-distance calls of free-living maned wolves in Ecological Station of Itirapina, São Paulo, Brazil
Authors: Campos Paula Bruna , Luchesi Lilian , Monticelli Patrícia
Published: May 2022

For the present study, we evaluated the long-distance vocalization of free-living maned wolves of the Ecological Station of Itirapina, São Paulo, Brazil. This population has been exposed to railway noise for at least 100 years, since the railroad activities, in 1916. For the present study, we aim to investigate long-distance calls of maned wolves in this area, verifying the presence and absence of calls during the railway noise. For six months, between February and December 2016, we collect data using passive acoustic monitoring systems. The evaluation data set comprised 600 h of file recordings. The measurement of sound activity used in this study was the occurrence of long-distance calls sequences and railway noise. To assess the variation of the occurrence in long-distance calls and railway noise, hourly calling rates were calculated. The railway noise was most frequent between 9 p.m. and 10 p.m. UTC. The time distribution of long-distance calls and railway noise varied between the 12 hours of record with more vocalizations from 12 a.m. to 3 a.m. UTC. Our results provided cues of how a vocally active mammal species may communicate in a noisy environment.
Black Soldier Fly Larvae Influence Internal and Substrate Bacterial Community Composition Depending on Substrate Type and Larval Density
Authors: Schreven Stijn J. J. , de Vries Hugo , Hermes Gerben D. A. , Zeni Giacomo , Smidt Hauke , Dicke Marcel , van Loon Joop J. A.
Published: May 2022

Black soldier fly larvae can process organic side streams into nutritious insect biomass, yielding a sustainable ingredient of animal feed. In processing such organic residues, the larvae impact the substrate and its microbiota.
Characterization of the Serpentine Adeno-Associated Virus (SAAV) Capsid Structure: Receptor Interactions and Antigenicity
Authors: Mietzsch Mario , Hull Joshua A. , Makal Victoria E. , Jimenez Ybargollin Alberto , Yu Jennifer C. , McKissock Kedrick , Bennett Antonette , Penzes Judit , Lins-Austin Bridget , Yu Qian , Chipman Paul , Bhattacharya Nilakshee , Sousa Duncan , Strugatsky David , Tijssen Peter , McKenna Robert , Agbandje-McKenna Mavis
Published: May 2022

AAVs are widely studied therapeutic gene delivery vectors. However, preexisting antibodies and their detrimental effect on therapeutic efficacy are a primary challenge encountered during clinical trials.
Virus-Host Interactions and Genetic Diversity of Antarctic Sea Ice Bacteriophages
Authors: Demina Tatiana A. , Luhtanen Anne-Mari , Roux Simon , Oksanen Hanna M.
Published: May 2022

Very little is known about sea ice microbes despite the significant role played by sea ice in the global oceans as well as microbial input into biogeochemical cycling. Studies on the sea ice viruses have been typically limited to -omics-based approaches and microscopic examinations of sea ice samples.
Recovery of Metagenome-Assembled Genomes from a Human Fecal Sample with Pacific Biosciences High-Fidelity Sequencing
Authors: Plaza Oñate Florian , Roume Hugo , Almeida Mathieu
Published: May 2022

Here, we report the recovery of 89 metagenome-assembled genomes (MAGs) derived from a human fecal sample subjected to Pacific Biosciences (PacBio) high-fidelity (HiFi) sequencing. A total of 9 MAGs consisted of complete circular contigs, and 45 MAGs were high-quality draft genomes according to the minimum information about a metagenome-assembled genome (MIMAG) standards.
How to use Twitter at a Scientific Conference
Authors: Power B. Joanne
Published: May 2022

In the past decade, social media platforms have been recognized as an important tool in the dissemination of science among the research community and as an interface between scientists and the general public. Publishing companies that specialize in scientific research now pay attention to alternative metrics (“altmetrics”) and provide comprehensive guides about social media management to editors.
Strain Variation in Clostridioides difficile Cytotoxicity Associated with Genomic Variation at Both Pathogenic and Nonpathogenic Loci
Authors: Saund Katie , Pirani Ali , Lacy D. Borden , Hanna Philip C. , Snitkin Evan
Published: May 2022

Clostridioides difficile
has two major disease-mediating toxins, A and B, encoded within the pathogenicity locus (PaLoc). In this study, we demonstrate via multiple approaches that genomic variants outside the PaLoc are associated with changes in cytotoxicity.
Mechanisms and Implications of Bacterial Invasion across the Human Skin Barrier
Authors: Lipsky Zachary W. , Patsy Marisa , Marques Cláudia N. H. , German Guy K.
Published: May 2022

Millions of people suffer from the chronic inflammatory skin disease atopic dermatitis (AD), whose symptoms are associated with a deficiency of skin lipids that exhibit antimicrobial functions and increased populations of the opportunistic pathogen
Staphylococcus aureus
. However, the pathogenesis of AD is ambiguous, and it remains unclear if these observed changes are merely the result of AD or contribute to the pathogenesis of the disease.
Early incubation and prolonged maturation of large ignimbrite magma bodies: Evidence from the Southern Rocky Mountain volcanic field, Colorado, USA
Authors: Lipman Peter W. , Zimmerer Matthew J. , Gilmer Amy K.
Published: May 2022

Clusters of early central volcanoes in the mid-Cenozoic Southern Rocky Mountain volcanic field (SRMVF; southwestern Colorado, USA) record sites of initial magmatic focusing that led to assembly of sizable upper-crustal magma bodies capable of generating large ignimbrites. Peak growth at precursor andesitic volcanoes was followed by extended periods (0.5 to >2 m.y.) of reduced eruptive activity during inferred prolonged incubation of the crustal reservoir prior to eruption of ignimbrites at the San Juan magmatic locus, as exemplified by the 5000 km3 Fish Canyon Tuff and associated La Garita caldera. After a magma system became thermally mature and compositionally evolved, additional large ignimbrites could erupt more rapidly from polycyclic calderas. In contrast, incubation times for smaller ignimbrite magmas, as at Crater Lake, Oregon, were briefer than for San Juan systems. Plutonic counterparts to the temporal-compositional assembly of arc-ignimbrite magmas are exemplified by incrementally emplaced granitoid intrusions like the Mesozoic Tuolumne complex in the Sierra Nevada.
Comparison of the Pipeline embolisation device alone or combined with coiling for treatment of different sizes of intracranial aneurysms
Authors: Wang Chao , Luo Bin , Li Tianxiao , Maimaitili Aisha , Mao Guohua , Song Donglei , Wang Yunyan , Feng Wenfeng , Wang Yang , Shi Huaizhang , Wan Jieqing , Liu Jianmin , Guan Sheng , Zhao Yuanli , Zhang Hongqi
Published: May 2022

Objectives

The aim of this study was to compare complications and outcomes between intracranial aneurysms treated with the Pipeline embolisation device (PED) alone or with PED combined with coiling for different-sized aneurysms.

Method

Patients with aneurysms treated by PED were collected from the PED in China postmarket multicentre registry study. We performed a propensity match analysis to compare the efficacy and safety between PED alone and PED combined with coiling treatment, and then aneurysms were organised into three groups based on their size: small (≤7 mm), medium (≤15 mm to >7 mm) and large/giant (>15 mm). Complications and aneurysm occlusion rates in the aneurysm size groups were compared between PED alone and PED combined with coiling patients.

Result

A total of 1171 patients with 1322 aneurysms were included. All patients received clinical follow-up, while angiographic follow-up was available in 967 aneurysms. For small aneurysms, there was no difference in the aneurysm occlusion rate between two groups (79.1% vs 88.4%, respectively), while there was a significant increase in the ischaemic complication rate (8.3% vs 19.3%, respectively, p=0.0001). For medium and large/giant saccular aneurysms, PED combined with coiling significantly improved the occlusion rate (medium aneurysms: 74.7% vs 88.8%, respectively, p<0.0001; large/giant saccular aneurysms: 72.9% vs 86.9%, respectively, p=0.018), while there were no differences in the total complication rate. For large/giant non-saccular aneurysms, two groups showed no differences.

Conclusion

Use of the PED with adjunctive coils can significantly improve the occlusion rate of medium aneurysms, without increasing the total complication rate.
Cosmological sudden singularities in f(R, T) gravity
Authors: Gonçalves Tiago B. , Rosa João Luís , Lobo Francisco S. N.
Published: May 2022

In this work, we study the possibility of finite-time future cosmological singularities appearing in f(R, T) gravity, where R is the Ricci scalar and T is the trace of the stress-energy tensor. We present the theory in both the geometrical and the dynamically equivalent scalar–tensor representation and obtain the respective equations of motion. In a background Friedmann–Lemaître–Robertson–Walker (FLRW) universe with an arbitrary curvature and for a generic $$C^\infty $$

C
∞

function f(R, T), we prove that the conservation of the stress-energy tensor prevents the appearance of sudden singularities in the cosmological context at any order in the time-derivatives of the scale factor. However, if this assumption is dropped, the theory allows for sudden singularities to appear at the level of the third time-derivative of the scale factor a(t), which are compensated by divergences in either the first time-derivatives of the energy density $$\rho (t)$$

ρ
(
t
)

or the isotropic pressure p(t). For these cases, we introduce a cosmological model featuring a sudden singularity that is consistent with the current measurements for the cosmological parameters, namely, the Hubble constant, deceleration parameter, and age of the universe, and provide predictions for the still unmeasured jerk and snap parameters. Finally, we analyse the constraints on a particular model of the function f(R, T) that guarantees that the system evolves in a direction favorable to the energy conditions at the divergence time.
Stochastic Optimization of Multiple Tuned Inerter Dampers for Mitigating Seismic Responses of Bridges with Friction Pendulum Systems
Authors: Wen Yongkui , Hui Bo
Published: May 2022

Friction pendulum systems (FPSs) are increasingly being used for bridge seismic isolation, and the isolated response is generally achieved at the expense of inducing large bearing displacements. Setting up a tuned inerter damper (TID) is an approach for improving seismic performance. Nevertheless, the optimization and performance enhancement of multiple TIDs to mitigate the seismic responses of bridges isolated with the FPSs are limited. In this study, the stochastic optimization of multiple TIDs for controlling stochastically excited bridges with FPS bearings was pursued. By describing the hysteretic characteristics of the FPS using the Bouc–Wen model, augmented systems of the bridge model, FPS bearings, and TIDs were formulated and combined with the modeling of stochastic excitation as filtered Gaussian white noise. A stochastic optimization procedure of multiple TIDs for controlling the bridge response considering the nonlinearity of the FPS bearings is proposed and illustrated using examples of continuous bridges. The effects of FPS friction on the optimization and robustness of the TID parameters were identified. A parametric study was performed to determine the mechanism of TID performance enhancement depending on the number of TIDs, multiple modes of tuning, and inertance distribution. Numerical results indicate that the TIDs designed via stationary-stochastic-global (SSG) optimization significantly reduced the responses of the isolated bridge, and the performance was improved by increasing the TID number. Considering the multi-mode contributions to the transversal responses, the performance of spatially distributed TIDs can be substantially enhanced by adding the TID inertance as a design parameter.
ANALYSIS OF INDUCED ISOMETRIC FATIGUING CONTRACTIONS IN BICEPS BRACHII MUSCLES USING MYOTONOMETRY AND SURFACE ELECTROMYOGRAPHIC MEASUREMENTS
Authors: BANERJEE SHIB SUNDAR , SADHUKHAN DEBOLEENA , ARUNACHALAKASI AROCKIARAJAN , SWAMINATHAN RAMAKRISHNAN
Published: May 2022

Viscoelastic properties of skeletal muscle tissue are known to be impacted by fatiguing contractions. In this study, an attempt has been made to utilize myotonometry for analyzing the relationship between muscle viscoelasticity and contractile behaviors in a fatiguing task. For this purpose, thirteen young healthy volunteers are recruited to perform the fatiguing isometric task and the time to task failure (TTF) is recorded. Myotonometric parameters and simultaneous surface electromyographic (sEMG) signals are recorded from the Biceps Brachii muscle of the flexed arm. The correlation between myotonometric parameters and TTF is further analyzed. Cross-validation with sEMG features is also performed. Stiffness of muscle has a positive correlation with TTF in the left hand ([Formula: see text]). Damping property of the nonfatigued muscle is positively associated with the fatigue-induced changes in amplitude features of sEMG signal in the right hand ([Formula: see text]). The normalized rate of change of mean frequency of sEMG signal has a positive correlation with stiffness values in both of the hands ([Formula: see text]). Muscle viscoelasticity is demonstrated to influence the progression of fatigue, although the difference in motor control due to handedness is also found to be an important factor. The results are promising to improve the understanding of the effect of muscle mechanics in fatigue-induced task failure.
Entrepreneurs’ Level of Awareness on Knowledge Management for Promoting Tourism in Nepal
Authors: Kharel Saramsh , K C Anup , Devkota Niranjan , Paudel Udaya Raj
Published: May 2022

Managing knowledge in the field of tourism and the hospitality industry will carry significant importance as most people are not aware of knowledge management (KM) implications. As the importance of knowledge management is not well captured in the tourism sector of Nepal, this study aims to identify the awareness level of knowledge management among the tourism entrepreneurs in Nepal and suggest managerial implications for the same. The primary data were collected through 276[Formula: see text]questionnaire surveys. Tourism entrepreneurs saw the benefits of KM for tourism development despite the costs and challenges it poses. Awareness of knowledge management of entrepreneurs differs according to the people, process, technology, organization structure, and the organization culture dimension. It was further influenced by the demographic characteristics of the tourism entrepreneurs. Enterprises are in more need of knowledge management awareness and several amendments in tourism development policies and programs. Therefore, this study recommends increasing entrepreneurs’ awareness of knowledge management by the joint effort of tourism enterprises and the Nepal Tourism Board. Various knowledge management seminars (integrating tourism experts with tourism entrepreneurs) and training programs should be conducted to manage knowledge effectively.
Statistically Empirical Integrated Approach for Knowledge Refined Text Classification
Authors: Sailaja N. Venkata , Sree L. Padma , Mangathayaru N.
Published: May 2022

Automated text mining is an especially important task in modern data analysis, both from theoretical and experimental points of view. This particular problem has a major interest in the digital age that is related to “Artificial Intelligence, Machine learning and Information Retrieval”. Feature selection and classification of high dimensionality of text data are challenging tasks. In this paper, we adopted an optimal method for dealing with high dimensionality of data. Later, we chose an appropriate strategy (learning algorithm) for an effcient model training. Our empirical evaluation and experimental analysis show that the proposed method performs better compared with other variable selection-based dimension reduction and further text categorisation methods. We exploited several systematic and careful experimentation scenarios in this work to discover what architecture works best for this BBC news dataset. We used 3 hidden layers, each layer with 128 neurons. We observed this architecture optimal as per our specific problem experimentation. Moreover, our proposed method can be useful for improving efficiency and speed-up the calculations on certain datasets.
Synthesis and Assessment of Lipid Nanovesicles for Efficient Transdermal Delivery of Hydrophilic Molecules
Authors: Singh Mahendra , Lee Kyung Eun , Vinayagam Ramachandran , Kang Sang Gu
Published: May 2022

The transdermal delivery of hydrophilic molecules through the dermis is a challenging task because of the various skin barriers. Thus, lipid nanovesicles, including liposomes, ethosomes and transethosomes, are advantageous to transdermal drug delivery. This study was designed to develop nanovesicles like liposomes (LF1), ethosomes (EF1) and transethosomes (TF1) containing hydrophilic agents such as Rhodamine B (RB) as a model compound. Nanovesicles loaded with RB were synthesized using an ethanol injection method followed by probe sonication (hot method). The nonsonicated nanovesicles had vesicle sizes ranging from [Formula: see text] to [Formula: see text][Formula: see text]nm, while sonicated nanovesicles sizes ranged from [Formula: see text] to [Formula: see text][Formula: see text]nm. In addition, the nonsonicated nanovesicles had polydispersity index (PdI) ranging from [Formula: see text] to [Formula: see text], whereas the PdI of the sonicated nanovesicles ranged from [Formula: see text] to [Formula: see text]. Transmission electron microscopy revealed the distinguishable features of the sonicated nanovesicles depending on the compositions. The entrapment efficiency of RB was observed in the order of [Formula: see text]. At the end of 10[Formula: see text]h, RB permeated through the Strat-M[Formula: see text] membrane at [Formula: see text], [Formula: see text] and [Formula: see text]g/cm2 from the LF1, EF1 and TF1 containing RB, respectively. The flux ([Formula: see text]) of TF1 was obtained 5.53 times higher than RB itself. Therefore, the TF1 nanovesicle allowed the highly efficient permeation and entrapment of hydrophilic RB compared to LF1 and EF1 nanovesicles. Hence, it can be concluded that transethosomes would be a better choice for hydrophilic compounds to cross the skin barriers via the transdermal route.
Photocatalytic Reduction of CO2 by TiO2 Nanotubes
Authors: Chang H.-H. , Wei L.-W. , Huang H.-L. , Chang H.-Y. , Wang H. Paul
Published: May 2022

Continuously increasing atmospheric concentrations of CO2 have given rise to great concerns about climate change. Photocatalytic reduction of CO2 to chemicals by solar energy is considered a green and sustainable process. Interactions between CO2 molecules and photocatalysts surfaces are the key factors that affect photocatalytic reduction efficiency. Thus, a better understanding of their reactive species on the TiO2 nanotube (TNT) surfaces by in situ FTIR spectroscopy was studied in the present work. The FTIR absorbance features at 1303[Formula: see text]cm[Formula: see text] and 1393[Formula: see text]cm[Formula: see text] were associated with carbonate species, e.g., bidentate carbonate on the TNT. Complete desorption of CO2 from the TNT occurred at [Formula: see text][Formula: see text]K. The carboxylate species that were adsorbed on the TNT may conduct the surface reactions enhanced by UV–Vis light to yield low carbon chemicals.
TIME–FREQUENCY ANALYSIS BETWEEN ECONOMIC RISK AND FINANCIAL RISK IN THE MINT NATIONS: WHAT CAUSES WHAT?
Authors: ADEBAYO TOMIWA SUNDAY , KIRIKKALELI DERVIS , RJOUB HUSAM
Published: May 2022

This paper addresses a deficiency in the existing literature by examining the time–frequency domain association between economic risk (ER) and financial risk (FR) for the Mexico, Indonesia, Nigeria and Turkey (MINT) nations using dataset from 1984 to 2018. To the authors’ awareness, the relationship between economics and finance has not been thoroughly investigated in the context of risk for the MINT nations. As a result, the outcomes of this research are anticipated to provide an insight on and initiate a fresh discussion regarding the financial-economic nexus. The Breitung and Candelon (BC) causality and the wavelet coherence (WTC) techniques are used to inspect the combined time–frequency causal interrelationship between FR and ER, in accordance with the study goals. The findings from the wavelet revealed the following: (i) a one-way causality exists from ER to FR in Mexico; (ii) a one-way causality exists from FR to ER in Indonesia; (iii) a unidirectional causality exists from ER to FR in Nigeria and (iv) a one-way causality exists from FR to ER in Turkey. Furthermore, the BC causality outcomes validate the WTC outcomes. The study findings are critical for both researchers and macroeconomic policymakers and can be utilized to make appropriate measures, if necessary, by adopting alternative or more appropriate financial and economic decisions.
A Conceptual Model to Assess the Literacy of Water Consumers
Authors: Fernandes Ana , Figueiredo Margarida , Neves José , Vicente Henrique
Published: May 2022

A conceptual model to assess the literacy level of water consumers is presented. On the one hand, a literature search was performed using the ScienceDirect and B-On platforms, conjoining the terms literacy, awareness, water, water for human consumption, drinking water, environmental, disease prevention and public health, resulting in seven papers with the mingle of literacy and water and five on literacy and the environment being uncovered. On the other hand, the lack of papers and information on the subject caused us to consider developing a conceptual model to transform the processes of planning and operationalization of the studies of literacy of water consumers. The model can support the development and validation of measurement tools capable of apprehending different dimensions in the context of water literacy. A questionnaire was conceived and applied to a cohort of 147 respondents in order to assess water literacy. In addition, the articulation of the proposed model and Deming’s PDCA model was demonstrated in order to achieve excellence through the evaluation of the current reality to promote improvement solutions.
Boosting Inter-process Communication with Architectural Support
Authors: Xia Yubin , Du Dong , Hua Zhichao , Zang Binyu , Chen Haibo , Guan Haibing
Published: May 2022

IPC (inter-process communication) is a critical mechanism for modern OSes, including not only microkernels such as seL4, QNX, and Fuchsia where system functionalities are deployed in user-level processes, but also monolithic kernels like Android where apps frequently communicate with plenty of user-level services. However, existing IPC mechanisms still suffer from long latency. Previous software optimizations of IPC usually cannot bypass the kernel that is responsible for domain switching and message copying/remapping across different address spaces; hardware solutions such as tagged memory or capability replace page tables for isolation, but usually require non-trivial modification to existing software stack to adapt to the new hardware primitives. In this article, we propose a hardware-assisted OS primitive,
XPC
(Cross Process Call), for efficient and secure synchronous IPC. XPC enables direct switch between IPC caller and callee without trapping into the kernel and supports secure message passing across multiple processes without copying. We have implemented a prototype of XPC based on the ARM AArch64 with Gem5 simulator and RISC-V architecture with FPGA boards. The evaluation shows that XPC can reduce IPC call latency from 664 to 21 cycles, 14×–123× improvement on Android Binder (ARM), and improve the performance of real-world applications on microkernels by 1.6× on Sqlite3.