bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of the Orthotropic Elastic Tensor of Composites Using Full Field Lamb Wave Energy Velocities and Dispersion Curves
Authors: Orta Adil Han , Azadi Shain , Hedayatrasa Saeid , Roozen Nicolaas Bernardus , Van Paepegem Wim , Kersemans Mathias , Van Den Abeele Koen
Published: January 2022

A multi-objective inversion procedure is proposed based on 3D Lamb wave dispersion curves and energy velocity matching to identify the elastic stiffness tensor of orthotropic composite plates. To validate the procedure, finite element model simulations and experimental measurements have been conducted on an aluminum and a composite plate by using piezoelectric actuator broadband signals. Experimentally, the in-plane and out-of-plane velocity components on the surface of these plates were measured using a 3D Infrared Scanning Laser Doppler Vibrometer. By exploiting Fourier Transform, the measured space-time domain data is converted into the frequency-wavenumber domain, from which dispersion curves are extracted. To identify the energy velocity, Short Time Fourier Transform and linear Radon transformation have been applied. Then, image processing is used both for dispersion and energy velocity curves to match the amplitude of the in-plane and out-of-plane velocities on the surface of the plate. The Semi Analytical Finite Element method (SAFE) was selected as the forward model to be embedded in an inversion algorithm due to its accuracy and robustness. Using a multi-objective genetic algorithm, the elastic tensor is calculated by simultaneously minimizing the error between (i) the measured and calculated dispersion curves on one hand, and (ii) the measured and calculated energy velocity slowness curves on the other hand for every in and out of plane velocity measurement. The mean values of the pareto front are selected as optimum parameters. The reconstructed elastic stiffness properties show good agreement with less than 6% average deviation.
Acoustic Magnifying Lens Based on Compact Non-Dispersive Spiral Metamaterial Array
Authors: Xiang Li , Jian Li , Xinjing Huang
Published: January 2022

Acoustic magnifying lenses are utilized in a diversity of applications, from nondestructive detection of damages in materials to biomedical imaging. Acoustic metamaterials (MMs) provide powerful control over sound waves by using periodic structures made from natural materials. Existing acoustic meta-lens are commonly associated with designing dispersive metamaterial or connect with local resonator, thus resulting in inevitable deformity of waveforms. Although the four-blade spiral MMs has non-dispersive properties, how to further improve the transmission and reduce the manufacturing difficulty in a compact size is important to construction of a meta-lens.

We propose a single-blade spiral metamaterial, which has higher transmission and non-dispersion properties. Based on this meta-unit, we designed and manufactured a meta-lens with the ability to amplify sound signals at the focus point. Different from previous research, the meta-lens is established by periodic meta-helicoid unit and presents great focusing ability while maintaining a compact volume. We show, both theoretically and experimentally, the thin flat acoustic magnifier can turn normally incident signals focusing on the prescribed point and augmenting pressure amplitude about three times. Moreover, the diameter of each element is only 10 mm, and the thickness of the meta-lens is 48mm. Our new strategy may offer an alternate route to the design of novel meta-lens and devices for acoustic application in the future.
Assessment of Damage in Metallic Plates by Ultra-Wideband Guided Electromagnetic Waves
Authors: Memmolo Vittorio , Moll Jochen , Nguyen Duy Hai , Krozer Viktor , Holstein Jakob , Kapoor Rohit , Stindl Jonathan
Published: January 2022

Guided electromagnetic wave propagation using ultra-wideband signals is a barely new approach for damage detection. However, still many challenges are present, including the way to deal with the GHz domain signals and the physics behind the interaction phenomena enabled by any type of flaw. The present work proposes a feasibility analysis for a structural health monitoring system employing permanently integrated microwave sensors. This setup allows to interrogate the structure continuously using multiple transmitters and multiple receivers when the electromagnetic waveguide is established. To this end, a metallic plate is equipped with a dielectric waveguide patch attached to the structures’ surface. To validate the detectability of damage, a reversible defect is modeled through removable bolts accessible from the other surface of the plate. The experiments are carried out considering different bottom holes at different spatial locations of the plate. In addition, concurrent measurements are adopted to characterize the noise level within the signal. The characteristic changes of electromagnetic wave signals are caught using a damage index approach returning whether the defect can be detected sensitively or not. Different coupling conditions are used to let the guided electromagnetic waves propagate and interact with underlaying structure. The results show that this approach can be adopted for damage detection with a reasonable signal to noise ratio, especially when the waveguide is well coupled. In addition, both transmission and reflection loss can be monitored reliably.
Reduced False Calls in Eddy Current Images Using Signal Processing
Authors: Mahalakshmi S. B. , Seshadri Ganesh , Sheila-Vadde Aparna , Kumar KM Manoj
Published: January 2022

Non-destructive testing methods are used largely in component manufacturing industries like Aerospace, Renewables and Power to evaluate the properties of a material or the quality of a component by inspecting for cracks and discontinuities without causing damage to the part. Among the many non-destructive testing methods, Eddy current imaging enables efficient flaw detection for surface and sub-surface cracks. However, in typical eddy current inspection, there can be significant number of false calls arising from variation in lift-off and surface anomalies. Discriminating defect signals from false calls can be very challenging. This paper describes a method to reduce false calls by using a wavelet based denoising algorithm and combining it with statistical-based features extracted inside a sliding window in the time domain to efficiently identify the cracks. The results are verified on specimens with cracks of different sizes that are oriented randomly along with locations available for baseline noise measurements.
In-Situ Laser Ultrasound Measurements of Austenitic Grain Growth in Plain Carbon Steel
Authors: Kerschbaummayr Christian , Ryzy Martin , Reitinger Bernhard , Hettich Mike , Džugan Jan , Wydra Thomas , Scherleitner Edgar
Published: January 2022

The macroscopic mechanical properties like yield-strength, ductility or hardness play an important role during the steel production and the design of new steel grades. The austenite grain size is an important parameter, which influences the final microstructure and the properties of a material. When developing grain growth evolution models, typically many samples have to be treated thermally and micrographs have to be prepared ex-situ. To reduce the time expenditure of this procedure we carried out in-situ laser ultrasound measurements of austenitic grain growth in plain carbon steel (AISI 1045). A thermomechanical simulator of the type Linseis L78/RITA has been upgraded with a laser ultrasound measurement system, which enables the continuous and contactless determination of the austenite mean grain size during a thermal cycle. In this work we will show the calibration workflow and grain size results by a new attenuation model for plain carbon steel. In-situ laser ultrasound measurement data is compared with several micrographs defined at supporting points along a specified temperature program to corroborate the findings.
Nondestructive Evaluation of Materials Tensile Strength via Nonlinear Acoustics Data
Authors: Ehrler Julian , Solodov Alexander , Bernhardt Yannick , Kreutzbruck Marc
Published: January 2022

The nonlinear acoustic approach is assessed for applications as a nondestructive tool for reconstructing stress-strain curves and quantifying the ultimate tensile strength for variety of materials. The direct algorithm uses the polynomial stress-strain expansion up to the third power of strain and the literature data on the second-order nonlinearity parameters to calculate relevant segments of the stress-strain curves. Since the third-order nonlinearity parameters are unknown for majority of materials the calculations used an iteration scheme to obtain closer approximations to the experimental data available from static tensile tests. The solution to the inverse problem identifies the range of the nonlinearity parameters for a given tensile strength and enables to categorize the contribution of the quadratic and cubic nonlinearities in mechanical response for different materials.
Coda Waves for Health Monitoring of Composites Under Low-Velocity Impact
Authors: Sharma Subal , Dayal Vinay
Published: January 2022

Coda waves have been shown to be sensitive to lab-controlled defects such as very small holes in fibrous composite material. In the real world, damages are subtler and more irregular. The main objective of this work is to investigate coda wave capability to detect low-velocity impact damages. The emphasis is to detect the presence of barely visible impact damages using ultrasonic waves. Detection of incipient damage state is important as it will grow over the life of the structure. Differential features, previously used in similar work, have been utilized to detect realistic impact damages on carbon fiber composites. Quasi-isotropic composite laminates were subjected to low-velocity impact energy ranging from 2J to 4.5J. Two differential features reported could be used detect the presence of damage. It is also observed that ply orientation can be a deterministic factor for indicating damages. The size and shape of the impact damage has been characterized using ultrasonic C-scans. Results indicate that coda waves can be used for the detection of damage due to low-velocity impact.
Feasibility of Lead Fast Reactor Heat Exchanger Tube Online Monitoring
Authors: Glass S. W. , Good M. S. , Hirt E. H.
Published: January 2022

Online structural health corrosion monitoring in advanced lead fast reactor heat exchangers and molten salt reactor heat exchangers is desirable for detecting tube degradation prior to leaks that may allow mixing of heat exchanger fluids or release of radiological contamination beyond the design containment boundary. This program demonstrates feasibility for a torsional mode sensor to attach to the outside of a long (30-m) heat-exchanger tube in the stagnant flow area where the tube joins the heat-exchanger plenum and where it is possible to protect a sensor and cable from high-force flows. The sensor must be connected by a cable to a monitoring instrument near the heat exchanger. The sensor and cable management approach will be impractical to implement on existing heat exchangers; rather, sensors must be installed in conjunction with heat exchanger fabrication. Previous work has shown the ability of low-temperature lead zirconate titanate (PZT) piezoceramic sensors to detect anomalies of interest in 3-m tubes. These sensors have subsequently been extended to a 30-m tube more representative of commercial power heat exchanger designs. The program will continue to investigate higher-temperature piezoelectric ceramics and long-term performance of high-temperature adhesives and sealants for 350 C lead reactor environments and higher-temperature (700 °C) molten salt environments.
In memory of Gary Bauchan: Utilizing an integrated taxonomy approach for the description of a new species of Gamasellodes (Mesostigmata: Ascidae)
Authors: Rueda-ramírez Diana , Santos Jandir C. , Young Monica R. , Mowery Joseph , Bauchan Gary , Ochoa Ronald , Palevsky Eric
Published: January 2022

Gamasellodes garybauchani sp. nov. Rueda-Ramírez & Santos is described based on specimens collected at the Beltsville Agricultural Research Center (BARC) (Maryland, USA). Twenty-one specimens were used for the description, of which five were subjected to low temperature scanning electron microscopy (LTSEM), followed by DNA extraction for genetic analysis and subsequent slide mounting. The remaining 16 specimens were subjected to only DNA extraction for genetic analysis and subsequent slide mounting. Morphological characters of the new species observed both in the images obtained in LTSEM and in the observation of the mounted specimens are detailed. Molecular information available on the Barcode of Life Datasysetm (BOLD) is presented. An update to the recent key to the Gamasellodes species is provided.
Weighted pressure matching with windowed targets for personal sound zones
Authors: Molés-Cases Vicent , Elliott Stephen J. , Cheer Jordan , Piñero Gema , Gonzalez Alberto
Published: January 2022

Personal sound zones (PSZ) systems use an array of loudspeakers to render independent audio signals to multiple listeners within a room. The performance of a PSZ system, designed using weighted pressure matching, depends on the selected target responses for the bright zone. In reverberant environments, the target responses are generally chosen to be the room impulse responses from one of the loudspeakers to the control points in the selected bright zone. This approach synthesizes the direct propagation component and all the reverberant components in the bright zone, while minimizing the energy in the dark zone. We present a theoretical analysis to show that high energy differences cannot be achieved for the diffuse reverberant components in the bright and dark zones, and so trying to synthesize these components in the bright zone does not lead to the best performance. It is then shown that the performance can be improved by using windowed versions of these measured impulse responses as target signals, in order to control which reverberant components are synthesized in the bright zone and which are not. This observation is supported by experimental measurements in two scenarios with different levels of reverberation.
Wind speed and direction estimation based on the spatial coherence of closely spaced microphones
Authors: Mirabilii Daniele , Habets Emanuël A. P.
Published: January 2022

Wind-induced noise recorded with a compact microphone array can be exploited to infer the mean velocity of the free-field airflow. In this work, a model-based method to estimate the wind flow speed and direction is proposed that uses spectro-spatial correlations of closely spaced microphone signals. As shown in a recent work by the present authors, the normalized cross-power spectral density of flow-induced noise measured with closely spaced microphones, also referred to as the spatial coherence, can be approximated by a semi-empirical model, named the Corcos model. Due to the dependency of the Corcos model on the airflow velocity, the measured spatial coherence provides information on the sought quantity. Speed and direction can be resolved by fitting the measured spatial coherence to the analytical Corcos model in the least squares sense. The accuracy of the proposed method is investigated across a range of wind speed between 0.5 and 12 ms−1 and all directions, using observation lengths from 5 s to 1 h. The audio samples under test were recorded indoors and outdoors and labeled by an ultrasonic anemometer. The evaluation results show that the accuracy can be increased by reducing the time resolution.
DNA Repair and Longevity Assurance in
Paramecium tetraurelia
Authors: Smith-Sonneborn Joan
Published: January 2022

At given doses and clonal ages, ultraviolet (UV) irradiation-induced DNA damage reduced clonal life-span, but when followed by photoreactivation, extension of clonal life-span was observed. If photoreactivation preceded the UV treatment, no significant beneficial effect was detected. Because studies of others have shown that photoreactivation repair monomerizes the UV-induced cyclobutane dimers in DNA but does not affect the other photoproducts, these result indicate that DNA damage can influence the duration of clonal life-span unless that damage is repaired. Repeated treatment with UV and photoreactivation resulted in significant mean and maximal clonal life-span extension when compared with those of untreated controls, and it is assumed that the rejuvenation effect was due to the correction or prevention of some age damage.

Reproduced with permission from
Science
. Copyright 1979 American Association for the Advancement of Science.

Joan Smith-Sonneborn, DNA Repair and Longevity Assurance in
Paramecium tetraurelia. Science
203
, 1115-1117 (1979).
Effects of Food Restriction on Aging: Separation of Food Intake and Adiposity
Authors: Harrison David E. , Archer Jonathan , Astle Clinton M.
Published: January 2022

Restricted feeding of rodents increases longevity, but its mechanism of action is not understood. We studied the effects of lifelong food restriction in genetically obese and normal mice of the same inbred strain in order to determine whether the reduction in food intake or the reduction in adiposity (the percentage of fatty tissue) was the critical component in retarding the aging process. This was possible because food-restricted obese (
ob/ob
) mice maintained a high degree of adiposity. In addition to determining longevities, changes with age were measured in collagen, immune responses, and renal function. Genetically obese female mice highly congenic with the C57BL/6J inbred strain had substantially reduced longevities and increased rates of aging in tail tendon collagen and thymus-dependent immune responses but not in urine-concentrating abilities. When their weight was held in a normal range by feeding restricted amounts, longevities were extended almost 50%, although these food-restricted
ob/ob
mice still had high levels of adiposity, with fat composing about half of their body weights. Their maximum longevities exceeded those of normal C57BL/6J mice and were similar to the longevities of equally food-restricted normal mice that were much leaner. Food-restricted
ob/ob
mice had greatly retarded rates of collagen aging, but the rapid losses with age in splenic immune responses were not mitigated. Thus, the extension of life-span by food restriction was inversely related to food consumption and corresponded to the aging rate of collagen. These results suggest that aging is a combination of independent processes; they show that reduced food consumption, not reduced adiposity, is the important component in extending the longevity of genetically obese mice.

Reproduced by permission.

David E. Harrison, Jonathan Archer, Clinton M. Astle, Effects of Food Restriction on Aging: Separation of Food Intake and Adiposity.
Proc. Natl. Acad. Sci. U.S.A.
81
, 1835-1838 (1984).
Aging Can Be Genetically Dissected Into Component Processes Using Long-Lived Lines of
Caenorhabditis elegans
Authors: Johnson Thomas E.
Published: January 2022

The aging process has been dissected by analysis of genetic variants of the nematode
Caenorhabditis elegans
. Long-lived recombinant inbred lines were generated; some of these lines have mean and maximum life-spans up to 70% longer than the wild type. Longer life results from a slowing of the characteristic exponential increase in mortality rate that is typical of aging populations in all species. The length of developmental periods and the length of the reproductive period are unrelated to increased life-span. Lengthened life is due entirely to an increase in postreproductive life span. Development, reproduction, and life-span are each under independent genetic control. General motor activity decays linearly with chronological age in all genotypes. The decay in general motor activity is correlated with and is a predictor of life-span, suggesting that both share at least one common rate-determining component

Reproduced by permission.

Thomas E. Johnson, Aging Can Be Genetically Dissected Into Component Processes Using Long-Lived Lines of
Caenorhabditis elegans. Proc. Natl. Acad. Sci. U.S.A.
84
, 3777-3781 (1987).
Genetic Analysis of Life-Span in
Caenorhabditis elegans
Authors: Johnson Thomas E. , Wood William B.
Published: January 2022

Crosses between Bristol and Bergerac strains of the self-fertilizing hermaphroditic nematode
Caenorhabditis elegans
do not show the heterosis effects for life-span that complicate analysis of interstrain crosses with
Drosophila
or mice. Instead, they yield F
l
progeny with life-spans similar to those of the parent strains. By analysis of life-span variation among progeny F
2
populations from such crosses and by two independent analyses of life-spans among recombinant inbred lines derived from F
2
individuals by 18 rounds of self-fertilization, we estimate that the heritability of life-span in
C. elegans
is between 20 and 50%. Recombinant inbred lines show a range in mean life-spans of 10 to 31 days as compared with life-spans of about 18 days for each of the two parental strains. We conclude that life-span variation in
C. elegans
has a substantial genetic component and that this organism offers promising opportunities for selective breeding of longer-lived strains and genetic analysis of senescence.

Reproduced by permission.

Thomas E. Johnson, William B. Wood, Genetic Analysis of Life-Span in
Caenorhabditis elegans. Proc. Natl. Acad. Sci. U.S.A.
79
, 6603-6607 (1982).
Selection for Delayed Senescence in
Drosophila melanogaster
Authors: Luckinbill Leo S. , Arking Robert , Clare Michael J. , Cirocco William C. , Buck Steven A.
Published: January 2022

Although theories of the evolution of senescence differ in the mode of action by which genes are thought to control the aging process, they all view the rate of senescence as an adaptable feature of life history and therefore modifiable by natural selection. Tests of theory, however, have generally yielded mixed results. The life-span of
Drosophila melanogaster
increased strongly in populations selected for late reproduction in these experiments. Delayed senescence was accompanied by a reduced early fecundity, suggesting pleiotropic genetic control of the aging process.

Reproduced by permission.

Leo S. Luckinbill, Robert Arking, Michael J. Clare, William C. Cirocco, Steven A. Buck, Selection for Delayed Senescence in
Drosophila melanogaster. Evolution
38
, 996-1003 (1984).
Laboratory Evolution of Postponed Senescence in
Drosophila melanogaster
Authors: Rose Michael R.
Published: January 2022

A general corollary of population genetic theories of senescence is that the culture of outbred laboratory populations using females of later ages should lead to the evolution of postponed senescence. This has been tested before, but the predicted results have not been consistently reproducible. An experiment of this kind was both repeated and replicated, using a previously studied
Drosophila melanogaster
population. The results uniformly corroborated the evolutionary theory of senescence. Senescence was consistently postponed. Other, anomalous, results are explained in terms of experimental artifact.

Reproduced by permission.

Michael R. Rose, Laboratory Evolution of Postponed Senescence in
Drosophila Melanogaster.
Evolution
38
, 1004-1010 (1984).
Weyl Fermion magneto-electrodynamics and ultralow field quantum limit in TaAs
Authors: Lu Zhengguang , Hollister Patrick , Ozerov Mykhaylo , Moon Seongphill , Bauer Eric D. , Ronning Filip , Smirnov Dmitry , Ju Long , Ramshaw B. J.
Published: January 2022

Infrared spectroscopy in high magnetic fields reveals the lowest quantum limit in a Weyl semimetal.
Computer-aided design of reversible hybridization chain reaction (CAD-HCR) enables multiplexed single-cell spatial proteomics imaging
Authors: Liu Xiaohao , Mao Dongsheng , Song Yuchen , Zhu Liucun , Isak Albertina N. , Lu Cuicui , Deng Guoli , Chen Feng , Sun Fenyong , Yang Yu , Zhu Xiaoli , Tan Weihong
Published: January 2022

Cyclic imaging of multiple proteins in a single cell is realized through CAD-HCR.
Superabsorption in an organic microcavity: Toward a quantum battery
Authors: Quach James Q. , McGhee Kirsty E. , Ganzer Lucia , Rouse Dominic M. , Lovett Brendon W. , Gauger Erik M. , Keeling Jonathan , Cerullo Giulio , Lidzey David G. , Virgili Tersilla
Published: January 2022

In a major step toward the development of a quantum battery, superabsorption has been achieved in an organic microcavity.
CDK4 and CDK6 kinases: From basic science to cancer therapy
Authors: Fassl Anne , Geng Yan , Sicinski Piotr
Published: January 2022

Targeting cyclin-dependent kinases

Cyclin-dependent kinases (CDKs), in complex with their cyclin partners, modulate the transition through phases of the cell division cycle. Cyclin D–CDK complexes are important in cancer progression, especially for certain types of breast cancer. Fassl
et al
. discuss advances in understanding the biology of cyclin D–CDK complexes that have led to new concepts about how drugs that target these complexes induce cancer cell cytostasis and suggest possible combinations to widen the types of cancer that can be treated. They also discuss progress in overcoming resistance to cyclin D–CDK inhibitors and their possible application to diseases beyond cancer. —GKA
Ultrahard magnetism from mixed-valence dilanthanide complexes with metal-metal bonding
Authors: Gould Colin A. , McClain K. Randall , Reta Daniel , Kragskow Jon G. C. , Marchiori David A. , Lachman Ella , Choi Eun-Sang , Analytis James G. , Britt R. David , Chilton Nicholas F. , Harvey Benjamin G. , Long Jeffrey R.
Published: January 2022

Magnetic effects of lanthanide bonding

Lanthanide coordination compounds have attracted attention for their persistent magnetic properties near liquid nitrogen temperature, well above alternative molecular magnets. Gould
et al
. report that introducing metal-metal bonding can enhance coercivity. Reduction of iodide-bridged terbium or dysprosium dimers resulted in a single electron bond between the metals, which enforced alignment of the other valence electrons. The resultant coercive fields exceeded 14 tesla below 50 and 60 kelvin for the terbium and dysprosium compounds, respectively. —JSY
An RNA exosome subunit mediates cell-to-cell trafficking of a homeobox mRNA via plasmodesmata
Authors: Kitagawa Munenori , Wu Peipei , Balkunde Rachappa , Cunniff Patrick , Jackson David
Published: January 2022

mRNA migration through plasmodesmata

In plants, certain transcription factors are produced in one cell but transported, sometimes as messenger RNA (mRNA), through plasmodesmata, channels between neighboring plant cells, where they act. This system helps to manage stem cell development. Kitagawa
et al
. now identify part of the machinery that manages this cell-to-cell transport. Transport of the mRNA encoding the KNOTTED1 homeobox transcription factor depends on Ribosomal RNA-Processing Protein 44 (AtRRP44A), which is a subunit of the RNA exosome. —PJH
Measuring the melting curve of iron at super-Earth core conditions
Authors: Kraus Richard G. , Hemley Russell J. , Ali Suzanne J. , Belof Jonathan L. , Benedict Lorin X. , Bernier Joel , Braun Dave , Cohen R. E. , Collins Gilbert W. , Coppari Federica , Desjarlais Michael P. , Fratanduono Dayne , Hamel Sebastien , Krygier Andy , Lazicki Amy , Mcnaney James , Millot Marius , Myint Philip C. , Newman Matthew G. , Rygg James R. , Sterbentz Dane M. , Stewart Sarah T. , Stixrude Lars , Swift Damian C. , Wehrenberg Chris , Eggert Jon H.
Published: January 2022

Terapascal iron-melting temperature

The pressure and temperature conditions at which iron melts are important for terrestrial planets because they determine the size of the liquid metal core, an important factor for understanding the potential for generating a radiation-shielding magnetic field. Kraus
et al
. used laser-driven shock to determine the iron-melt curve up to a pressure of 1000 gigapascals (see the Perspective by Zhang and Lin). This value is about three times that of the Earth’s inner core boundary. The authors found that the liquid metal core lasted the longest for Earth-like planets four to six times larger in mass than the Earth. —BG
Visualizing broken symmetry and topological defects in a quantum Hall ferromagnet
Authors: Liu Xiaomeng , Farahi Gelareh , Chiu Cheng-Li , Papic Zlatko , Watanabe Kenji , Taniguchi Takashi , Zaletel Michael P. , Yazdani Ali
Published: January 2022

The interaction between electrons in graphene under high magnetic fields drives the formation of a rich set of quantum Hall ferromagnetic (QHFM) phases with broken spin or valley symmetry. Visualizing atomic-scale electronic wave functions with scanning tunneling spectroscopy (STS), we resolved microscopic signatures of valley ordering in QHFM phases and spectral features of fractional quantum Hall phases of graphene. At charge neutrality, we observed a field-tuned continuous quantum phase transition from a valley-polarized state to an intervalley coherent state, with a Kekulé distortion of its electronic density. Mapping the valley texture extracted from STS measurements of the Kekulé phase, we could visualize valley skyrmion excitations localized near charged defects. Our techniques can be applied to examine valley-ordered phases and their topological excitations in a wide range of materials.
Lost and found
Dark and Magical Places: The Neuroscience of Navigation
Christopher Kemp
Norton, 2022. 256 pp.
Authors: Bécu Marcia , Doeller Christian F.
Published: January 2022

A lyrical meditation on wayfinding offers cultural context and hope for the navigationally challenged
SARS-CoV-2 Omicron variant: Antibody evasion and cryo-EM structure of spike protein–ACE2 complex
Authors: Mannar Dhiraj , Saville James W. , Zhu Xing , Srivastava Shanti S. , Berezuk Alison M. , Tuttle Katharine S. , Marquez Ana Citlali , Sekirov Inna , Subramaniam Sriram
Published: January 2022

The newly reported Omicron variant is poised to replace Delta as the most prevalent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant across the world. Cryo–electron microscopy (cryo-EM) structural analysis of the Omicron variant spike protein in complex with human angiotensin-converting enzyme 2 (ACE2) reveals new salt bridges and hydrogen bonds formed by mutated residues arginine-493, serine-496, and arginine-498 in the receptor binding domain with ACE2. These interactions appear to compensate for other Omicron mutations such as the substitution of asparagine for lysine at position 417 (K417N) that are known to reduce ACE2 binding affinity, resulting in similar biochemical ACE2 binding affinities for the Delta and Omicron variants. Neutralization assays show that pseudoviruses that display the Omicron spike protein exhibit increased antibody evasion. The increase in antibody evasion and the retention of strong interactions at the ACE2 interface thus represent important molecular features that likely contribute to the rapid spread of the Omicron variant.
Window of opportunity
Authors: Servick Kelly
Published: January 2022

When surgery to treat neurological conditions lets researchers peer into the brain, ethical questions abound
A subset of follicular helper-like MAIT cells can provide B cell help and support antibody production in the mucosa
Authors: Jensen Owen , Trivedi Shubhanshi , Meier Jeremy D. , Fairfax Keke C. , Hale J. Scott , Leung Daniel T.
Published: January 2022

We identify a MAIT cell subset expressing T follicular helper markers and show the ability of MAIT cells to support B cell responses in the mucosa.
Genome Assembly of the Ty1-Less Saccharomyces paradoxus Strain DG1768
Authors: Chen Jingxuan , McQueary Holly , Hall David W. , Philippsen Peter , Garfinkel David J. , Bergman Casey M.
Published: January 2022

Here, we report an essentially complete genome assembly for the Ty1-less
Saccharomyces paradoxus
strain DG1768 (derivative of strain 337) based on PacBio and Illumina shotgun sequence data. We also document the genetic alterations that make this yeast strain a key resource for Ty1 mobility studies.
Evaluation of the Healthy Eating Food Index (HEFI)-2019 measuring adherence to Canada’s Food Guide 2019 recommendations on healthy food choices
Authors: Brassard Didier , Elvidge Munene Lisa-Anne , St-Pierre Sylvie , Gonzalez Alejandro , Guenther Patricia M. , Jessri Mahsa , Vena Jennifer , Olstad Dana Lee , Vatanparast Hassan , Prowse Rachel , Lemieux Simone , L’Abbe Mary R. , Garriguet Didier , Kirkpatrick Sharon I. , Lamarche Benoît
Published: January 2022

The objective of this study was to evaluate the construct validity and reliability of the Healthy Eating Food Index-2019 (HEFI-2019), which was developed to measure adherence to Canada’s Food Guide 2019 (CFG-2019) recommendations on healthy food choices. Dietary intake data from 24-hour dietary recalls in the 2015 Canadian Community Health Survey-Nutrition were used for that purpose. Multidimensionality was examined using principal component analysis. Mean scores were compared among subgroups of the population. The association between scores and energy intake was assessed using Pearson correlations. Cronbach’s alpha was calculated to assess reliability. The estimated mean HEFI-2019 score (/80) was 43.1 (95% CI, 42.7 to 43.6) among Canadians aged 2 years and older. The first and 99th percentiles were 22.1 and 62.9 points. The mean HEFI-2019 score for smokers was 7.2 points lower than for non-smokers (95% CI, –8.5 to –5.9). The HEFI-2019 was weakly correlated with energy intake (r = –0.13; 95% CI, –0.20 to –0.06). The principal components analysis revealed at least 4 dimensions. Cronbach’s alpha was 0.66 (95% CI, 0.63 to 0.69). Evidence of construct validity and internal consistency support the use of the HEFI-2019 to assess adherence to CFG-2019’s recommendations on healthy food choices.

Novelty: Examination of the HEFI-2019’s psychometric properties is needed prior to implementation. Analyses support the construct validity and internal consistency of the HEFI-2019. Interpretation of the total HEFI-2019 score must be accompanied by its components’ scores, considering it assesses multiple dimensions of food choices.
Considering the Artifact Ecology when Supporting the Evolution of Practices - Analyzing the Parallel Journeys of Two Teleconsultation Software in a General Hospital
Authors: Cormi Clément , Abou-Amsha Khuloud , Tixier Matthieu , Lewkowicz Myriam
Published: January 2022

The growing use of teleconsultation, especially since the start of the Covid-19 pandemic, changes physicians' work at the hospital. In this paper, we set out to study how physicians have integrated teleconsultation into their healthcare practices. Moreover, we are interested in how teleconsultation software contributes to developing new medical practices and how the design of teleconsultation software can better support them. Based on 16 months of fieldwork in a general hospital that offers two different teleconsultation software, we have investigated teleconsultation practices through interviews and observations involving ten physicians doing teleconsultation and a telemedicine secretary. Unlike the existing informal remote care by phone, we observe that teleconsultation supports new formal healthcare practices, particularly for patient care management and inter-organizational cooperation. While analyzing the integration of teleconsultation in physicians' practices, we highlight that both pieces of software do not support those practices on equal terms according to their design. We argue that teleconsultation software design can limit the spread of these new healthcare practices and that the artifact ecology of physicians should be considered during the design process.
Fostering Communication
Authors: Fowler John , Zachry Mark , McDonald David W.
Published: January 2022

The period of transition for foster youth into independent adulthood is an important life stage, and one that has yet to be explored in HCI circles. We studied an online community centered on the experiences of former foster youth through the first year of its existence to better understand how online spaces are being used by this population. Our mixed-method study included the coding of all posts from the first year of the online community and offers a mix of quantitative and qualitative findings. These findings include alignments and gaps in an established descriptive framework from the field of social work as it relates to the online communication of former foster youth. It also includes how the domains from the framework co-occur, and some potential implications of these co-occurrences. Future research on this subject is warranted, particularly related to why former foster youth seek online platforms to engage in conversations on these topics and how effective community members perceive the platform to be in safely and securely facilitating their needs.
Towards a Conceptual Framework for Understanding the Challenges in Refugee Re-settlement
Authors: Almohamed Asam Hamed Abbas , Talhouk Reem , Vyas Dhaval
Published: January 2022

Upon arrival to a host community, refugees and asylum seekers face immense challenges to rebuild their social capital that is critical in the process of their resettlement. Developing a holistic understanding of these challenges can provide significant opportunities to inform designers and services providers working with this demography. We adopt the lens of social capital coupled with an inquiry into the heterogeneity of refugees and asylum seekers to gain a holistic understanding of various challenges that they with. We accordingly present a conceptual framework that has been iteratively built based on our four years of engagement with refugee communities. The framework highlights three important aspects: cultural backdrops, displacement-related stressors, and social resources in the host community. We offer several implications for technology design, policies, and the theory of social capital that can support members from these communities in their resettlement.
Explanation Strategies as an Empirical-Analytical Lens for Socio-Technical Contextualization of Machine Learning Interpretability
Authors: Benjamin Jesse Josua , Kinkeldey Christoph , Müller-Birn Claudia , Korjakow Tim , Herbst Eva-Maria
Published: January 2022

During a research project in which we developed a machine learning (ML) driven visualization system for non-ML experts, we reflected on interpretability research in ML, computer-supported collaborative work and human-computer interaction. We found that while there are manifold technical approaches, these often focus on ML experts and are evaluated in decontextualized empirical studies. We hypothesized that participatory design research may support the understanding of stakeholders' situated sense-making in our project, yet, found guidance regarding ML interpretability inexhaustive. Building on philosophy of technology, we formulated explanation strategies as an empirical-analytical lens explicating how technical explanations mediate the contextual preferences concerning people's interpretations. In this paper, we contribute a report of our proof-of-concept use of explanation strategies to analyze a co-design workshop with non-ML experts, methodological implications for participatory design research, design implications for explanations for non-ML experts and suggest further investigation of technological mediation theories in the ML interpretability space.
O-Minimal Invariants for Discrete-Time Dynamical Systems
Authors: Almagor Shaull , Chistikov Dmitry , Ouaknine Joël , Worrell James
Published: January 2022

Termination analysis of linear loops plays a key rôle in several areas of computer science, including program verification and abstract interpretation. Already for the simplest variants of linear loops the question of termination relates to deep open problems in number theory, such as the decidability of the Skolem and Positivity Problems for linear recurrence sequences, or equivalently reachability questions for discrete-time linear dynamical systems. In this article, we introduce the class of
o-minimal invariants
, which is broader than any previously considered, and study the decidability of the existence and algorithmic synthesis of such invariants as certificates of non-termination for linear loops equipped with a large class of halting conditions. We establish two main decidability results, one of them conditional on Schanuel’s conjecture is transcendental number theory.
The Privacy Paradox and Optimal Bias-Variance Trade-offs in Data Acquisition
Authors: Liao Guocheng , Su Yu , Ziani Juba , Wierman Adam , Huang Jianwei
Published: January 2022

While users claim to be concerned about privacy, often they do little to protect their privacy in their online actions. One prominent explanation for this "privacy paradox" is that when an individual shares her data, it is not just her privacy that is compromised; the privacy of other individuals with correlated data is also compromised. This information leakage encourages oversharing of data and significantly impacts the incentives of individuals in online platforms. In this extended abstract, we discuss the design of mechanisms for data acquisition in settings with information leakage and verifiable data. We summarize work designing an incentive compatible mechanism that optimizes the worst-case tradeoff between bias and variance of the estimation subject to a budget constraint, where the worst-case is over the unknown correlation between costs and data. Additionally, we characterize the structure of the optimal mechanism in closed form and study monotonicity and non-monotonicity properties of the marketplace.
Are Covert DDoS Attacks Facing Multi-Feature Detectors Feasible?
Authors: Reza Ramtin Amir , Towsley Don , Nain Philippe , de Souza e Silva Edmundo , Menasche Daniel S.
Published: January 2022

We state and prove the square root scaling laws for the amount of traffic injected by a covert attacker into a network from a set of homes under the assumption that traffic descriptors follow a multivariate Gaussian distribution. We numerically evaluate the obtained result under realistic settings wherein traffic is collected from real users, leveraging detectors that exploit multiple features. Under such circumstances, we observe that phase transitions predicted by the model still hold.
Different Electrochemical Behavior of Cationic Dopamine from Anionic Ascorbic Acid and DOPAC at CNT Yarn Microelectrodes
Authors: Shao Zijun , Venton B. Jill
Published: January 2022

Carbon nanotube yarn microelectrodes (CNTYMEs) have micron-scale surface crevices that momentarily trap molecules. CNTYMEs improve selectivity among cationic catecholamines because secondary reactions are enhanced, but no anions have been studied. Here, we compared fast-scan cyclic voltammetry (FSCV) of dopamine and anionic interferents 3,4 dihydroxyphenylacetic acid (DOPAC) and L-ascorbic acid (AA) at CNTYMEs and carbon fiber microelectrodes (CFMEs). At CFMEs, dopamine current decreases with increasing FSCV repetition frequency at pH 7.4, whereas DOPAC and AA have increasing currents with increasing frequency, because of less repulsion at the negative holding potential. Both DOPAC and AA have side reactions after being oxidized, which are enhanced by trapping. At pH 4, the current increases for DOPAC and AA because they are not repelled. In addition, AA has a different oxidation pathway at pH 4, and an extra peak in the CV is enhanced by trapping effects at CNTYMEs. At pH 8.5, co-detection of dopamine in the presence of DOPAC and AA is enhanced at 100 Hz frequency because of differences in secondary peaks. Thus, the trapping effects at CNTYMEs affects anions differently than cations and secondary peaks can be used to identify dopamine in mixture of AA and DOPAC with FSCV.
Application of Terpolymer Encapsulated Flame-Retardant Separator in Ni-Rich and High-Voltage Lithium-Ion Batteries
Authors: Huang Jinhong , Hong Mingyao , Li Guanjie , Li Weishan , Liao Youhao
Published: January 2022

Increasing the working voltage of a Ni-rich cathode is considered as the most effective way to enhance the energy density of lithium-ion batteries (LIBs). However, high energy density brings safety hazards in LIBs, resulting from the structural instability of the cathode material and the oxidative decomposition of carbonate electrolyte under high-voltage conditions. Directly adding the proper amount of flame retardant to the liquid electrolyte reduces the safety hazards, but causes rapid decay in electrochemical performance. To achieve a balance, flame retardant of triphenyl phosphate (TPP) is encapsulated by poly(butyl methacrylate-acrylonitrile-styrene) (P(BMA-AN-St)) terpolymer during the electrospinning process ascribed from different physical properties of surface energy and polarity. Compared with the self-extinguishing time (SET) of 89.5 s g−1 for commercial polyethylene (PE) separator, the SET value of PT11 separator (P(BMA-AN-St): TPP = 1:1 (w:w)) is sharply reduced to 23.0 s g−1, although both separators present the similar ionic conductivity of 0.8 × 10−3 S cm−1 at room temperature. Whether in half-cells of LiNi0.8Co0.15Al0.05O2/Separator/Li or full-cells of LiNi0.8Co0.15Al0.05O2/Separator/graphite, PE and PT11 separator show parallel cycle stability between 3.0 and 4.5 V. Thus, terpolymer encapsulated flame-retardant separator achieves both improved flame retardancy and competent electrochemical stability, making it become a good candidate for high-energy-density LIBs.
Investigation of Retinal Microcirculation in Diabetic Patients Using Adaptive Optics Ophthalmoscopy and Optical Coherence Angiography
Authors: Baltă Florian , Cristescu Irina-Elena , Mirescu Andrada-Elena , Baltă George , Zemba Mihail , Tofolean Ioana Teodora
Published: January 2022

The current research approaches the retinal microvasculature of healthy volunteers (17 subjects), patients with diabetes mellitus without retinopathy (19 subjects), and of diabetic patients with nonproliferative (17 subjects) and proliferative (21 subjects) diabetic retinopathy, by using adaptive optics ophthalmoscopy and optical coherence ophthalmoscopy angiography. For each imaging technique, several vascular parameters have been calculated in order to achieve a comparative analysis of these imaging biomarkers between the four studied groups. The results suggest that diabetic patients with or without diabetic retinopathy prove signs of retinal arteriole structural alterations, mainly showed by altered values of wall to lumen ratio, calculated for the superior or inferior temporal branch of the central retinal artery, near the optic nerve head, and significant changes of the vascular density in the retinal superficial capillary plexus. Both adaptive optics ophthalmoscopy and optical coherence ophthalmoscopy angiography are providing useful information about the retinal microvasculature from early onset of diabetic disease, having a promising diagnostic and prognostic role in the future.