bluuebunny/crossref_metadata_2025 huggingface dataset:
Metric-connection geometries on pre-Leibniz algebroids: A search for geometrical structure in string models
Authors: Dereli Tekin , Doğan Keremcan
Published: March 2021

Metric-affine and generalized geometries are arguably the appropriate mathematical frameworks for Einstein’s theory of gravity and low-energy effective string field theory, respectively. In fact, mathematical structures in a metric-affine geometry are constructed on the tangent bundle, which is itself a Lie algebroid, whereas those in generalized geometries, which form the basis of double field theories, are constructed on Courant algebroids. Lie, Courant, and higher Courant algebroids, which are used in exceptional field theories, are all known to be special cases of pre-Leibniz algebroids. As mathematical structures on these algebroids are essential in string models, it is natural to work on a more unifying geometrical framework. Provided with some additional ingredients, the construction of such geometries can all be carried over to regular pre-Leibniz algebroids. We define below the notions of locality structures and locality projectors, which are some necessary ingredients. In terms of these structures, E-metric-connection geometries are constructed with (possibly) a minimum number of assumptions. Certain small gaps in the literature are also filled as we go along. E-Koszul connections, as a generalization of Levi–Cività connections, are defined and shown to be helpful for some results including a simple generalization of the fundamental theorem of Riemannian geometry. The existence and non-existence of E-Levi–Cività connections are discussed for certain cases. We also show that metric-affine geometries can be constructed in a unique way as special cases of E-metric-connection geometries. Some aspects of Lie and Lie-type algebroids are studied, where the latter are defined here as a generalization of Lie algebroids. Moreover, generalized geometries are shown to follow as special cases, and various properties of linear generalized-connections are proven in the present framework. Similarly, uniqueness of the locality projector in the case of exact Courant algebroids is proven, a result that explains why the curvature operator, defined with a projector in the double field theory literature, is a necessity.
1D chain structure in 1T′-phase 2D transition metal dichalcogenides and their anisotropic electronic structures
Authors: Tang Chi Sin , Yin Xinmao , Wee Andrew T. S.
Published: March 2021

The quasi-metallic 1T'-phase is one of the notable polymorphic two-dimensional transition metal dichalcogenide phases and possesses a unique structure, comprising a one-dimensional zigzag transition metal chain along a single axis. This structure gives rise to unprecedented anisotropic electronic properties, including new anisotropic mid-infrared plasmon excitations. The emergence of highly correlated electronic modes in such anisotropic systems is relevant to the intrinsic electronic and optical properties of two-dimensional transition metal dichalcogenides. In this review, we highlight the unique features of these materials in their anisotropic quasi-metallic 1T'-phase, not found in the other structural phases. We discuss how this anisotropic structure brings about the onset of unique physical phenomena such as the electronic band inversion, anomalously large magnetoresistance, and intrinsic or induced superconductivity in multiple transition metal dichalcogenide systems. The unique structural properties of these systems have led to spatially resolved transport and optical properties that can be further manipulated for use in a wide variety of applications ranging from nano-electronics to ultra-sensitive photonic systems but also their incorporation in high performance field-electric transistors, photodetectors, hydrogen evolution reactions, and piezoelectric devices cater to technologies of the future.
AlInAsSb avalanche photodiodes on InP substrates
Authors: Kodati S. H. , Lee S. , Guo B. , Jones A. H. , Schwartz M. , Winslow M. , Pfiester N. A. , Grein C. H. , Ronningen T. J. , Campbell J. C. , Krishna S.
Published: March 2021

We report the gain, noise, and dark current characteristics of random alloy Al0.79In0.21As0.74Sb0.26 (hereafter AlInAsSb)-based avalanche photodiodes (APDs) on InP substrates. We observe, at room temperature, a low excess noise corresponding to a k value (ratio of impact ionization coefficients) of 0.018 and a dark current density of 82 μA/cm2 with a gain of 15. These performance metrics represent an order of magnitude improvement of the k-value over commercially available APDs with InAlAs and InP multiplication layers grown on InP substrates. This material is also competitive with a recently reported low noise AlAsSb on InP [Yi et al., Nat. Photonics 13, 683 (2019)], with a comparable excess noise and a room temperature dark current density almost three orders of magnitude lower at the same gain. The low excess noise and dark current of AlInAsSb make it a candidate multiplication layer for integration into a separate absorption, charge, and multiplication layer avalanche photodiode for visible to short-wavelength infrared applications.
Measurements of dynamic surface changes by digital holography for in situ plasma erosion applications
Authors: Smith C. D. , Biewer T. M. , Gebhart T. E. , Lindquist E. G. , Thomas C. E.
Published: March 2021

There are currently few viable diagnostic techniques for in situ measurement of plasma facing component erosion. Digital holography is intended to fill this gap. Progress on the development of single and dual CO2 laser digital holography diagnostics for in situ plasma facing component erosion is discussed. The dual laser mode’s synthetic wavelength allows the measurable range to be expanded by a factor of ∼400 compared to single laser digital holography. This allows the diagnostic to measure surface height changes of up to 4.5 μm in single laser mode and up to 2 mm in dual laser mode. Results include ex situ measurements of plasma eroded targets and also dynamic measurements of nm and μm scale motion of a target mounted on a precision translation stage. Dynamic measurements have successfully been made with the system operating in both single and dual laser modes, from ∼50 nm to ∼4 μm in single laser mode and up to ∼400 μm in dual laser mode (limited only by the stage speed and camera acquisition duration). These results demonstrate the feasibility of using digital holography to characterize plasma facing component erosion dynamically, i.e., during plasma exposure. Results of proof-of-principle in situ digital holographic measurements of targets exposed to an electrothermal arc plasma source are presented.
Supersaturation-triggered synthesis of 2D/1D phosphide heterostructures as multi-functional catalysts for water splitting
Authors: Bi Haohao , Li Bo , Zhang Jing , Pan Anlian , Jiang Lang , Huang Gui-Fang , Chang Sheng-Li , Huang Wei-Qing
Published: March 2021

Creative approaches for designing heterostructures that consist of different dimensional components are necessary for achieving highly efficient catalytic materials. Here, we report an in situ supersaturation-triggered growth of vertically aligned 2D CoFeP nanosheet/1D Fe-CoP nanowire (2D/1D CoFeP NS@Fe-CoP NW) heterostructures with open hierarchical architecture. The integrating 1D nanowires and 2D nanosheets and well-defined 2D–1D interfacial coupling possess enhanced charge transfer, more active sites, and favorable kinetics during electrolysis, resulting in superb electrocatalytic performance for hydrogen evolution reaction, oxygen evolution reaction (OER), and overall water splitting. Specifically, CoFeP NS@Fe-CoP NW heterostructures are efficient OER catalysts in alkaline solution with an overpotential of 250 mV at 30 mA cm−2, outperforming most reported non-noble metal phosphide electrocatalysts. This work provides a facile and scalable strategy to design non-noble metal catalysts with multifunctionality and high activity.
Computational approaches to point defect simulations for semiconductor solid solution alloys
Authors: Mirrielees Kelsey J. , Baker Jonathon N. , Bowes Preston C. , Irving Douglas L.
Published: March 2021

Despite their technological importance, studying the properties of alloys with first principles methods remains challenging. In cases of AlxGa1-xN and BaxSrx-1TiO3 (BST), whose most important properties are governed by point defects, explicit simulation can be a computationally demanding task due to the random occupation of Al and Ga on cation sites in AlGaN and Ba and Sr on A-sites in BST. In this work, interpolation between end member compounds is used as a first approximation to defect properties and concentrations in intermediate alloy compositions in lieu of explicit simulation. In AlGaN, the efficacy of Si and Ge as dopants for n-type Al-rich AlGaN is explored by considering self-compensating defects such as multi-donor vacancy complexes and Si and Ge DX configurations. In BST, variation of the high temperature defect chemistry of Mg and Fe is examined. The approach presented here is expected to be generally appropriate for first approximation of defect properties in semiconductors and dielectrics where the alloy is a random solid solution of the end members.
Ventilative meta-window with broadband low-frequency acoustic insulation
Authors: Shi Jinjie , Liu Chenkai , Liu Xiaozhou , Lai Yun
Published: March 2021

Soundproofing ventilation devices can block sound while allowing free airflow simultaneously, which have many important applications in daily lives. In this work, we theoretically design and experimentally implement a broadband low-frequency acoustic meta-window. The meta-window is composed of a central rectangular open area and 12 surrounding identical channels. The total ventilation area is 220 cm2. Interestingly, with a deep subwavelength thickness of 4 cm, such a meta-window can exhibit a large acoustic bandgap, leading to the effective blocking of more than 90% of the incident sound energy in the broad range of 605–1050 Hz. By cascading such acoustic devices, the sound blocking effect can be further improved. Our work realizes a large-area and ultrathin ventilative meta-window with the function of broadband low-frequency acoustic insulation.
CO2 adsorption on the pristine and reduced CeO2 (111) surface: Geometries and vibrational spectra by first principles simulations
Authors: Baumann Noah , Lan Jinggang , Iannuzzi Marcella
Published: March 2021

First principles simulations of carbon dioxide adsorbed on the ceria (CeO2) (111) surface are discussed in terms of structural features, stability, charge transfer, and vibrational modes. For this purpose, different density functional theory methods, such as Perdew-Burke-Ernzerhof (PBE) PBE and Hubbard correction, hybrid functionals, and different basis sets have been applied and compared. Both the stoichiometric and the reduced (111) surfaces are considered, where the electronic structure of the latter is obtained by introducing oxygen vacancies on the topmost or the subsurface oxygen layer. Both the potential energy surfaces of the reduced ceria surface and the adsorbate–surface complex are characterized by numerous local minima, of which the relative stability depends strongly on the electronic structure method of choice. Bent CO2 configurations in close vicinity to the surface oxygen vacancy that partially re-oxidize the reduced ceria surface have been identified as the most probable stable minima. However, the oxygen vacancy concentration on the surface turns out to have a direct impact on the relative stability of possible adsorption configurations. Finally, the vibrational analyses of selected adsorbed species on both the stoichiometric and reduced surfaces show promising agreement with previous theoretical and experimental results.
Characterization of signals for a Divertor Tokamak Test facility interferometer/polarimeter system
Authors: Fiorucci D. , Giudicotti L. , Innocente P. , Terranova D. , Mazzotta C. , Tudisco O.
Published: March 2021

In magnetically confined fusion experiments, laser interferometer/polarimeter systems allow one to determine plasma density, give valuable information on the internal magnetic fields, and contribute to the evaluation of the plasma magnetic equilibrium and to the real-time estimation of the q profile to allow feedback configuration control. This work presents an analysis of the interferometric and polarimetric signals of a multi-chord far-infrared interferometer/polarimeter for the divertor tokamak test facility, the new tokamak device currently under construction in Italy. The polarimetric signals are calculated both with approximate formulas and by solving the equation describing the evolution of the laser beam polarization inside the plasma using the Mueller formalism. The latter method correctly accounts for crosstalk between Faraday rotation and the Cotton–Mouton effect. The impact of the plasma birefringence on the interferometric phase shift is also studied, and it is found that a perturbation of the interferometric phase shift is present also in the case of an initial fixed linear polarization of the probe laser beam.
The inductively driven transmission line: A passively coupled device for diagnostic applications on the Z pulsed power facility
Authors: Myers Clayton E. , Lamppa Derek C. , Jennings Christopher A. , Gomez Matthew R. , Knapp Patrick F. , Kossow Michael R. , Lucero Larry M. , Moore James K. , Yager-Elorriaga David A.
Published: March 2021

The inductively driven transmission line (IDTL) is a miniature current-carrying device that passively couples to fringe magnetic fields in the final power feed on the Z Pulsed Power Facility. The IDTL redirects a small amount of Z’s magnetic energy along a secondary path to ground, thereby enabling pulsed power diagnostics to be driven in parallel with the primary load for the first time. IDTL experiments and modeling presented here indicate that IDTLs operate non-perturbatively on Z and that they can draw in excess of 150 kA of secondary current, which is enough to drive an X-pinch backlighter. Additional experiments show that IDTLs are also capable of making cleaner, higher-fidelity measurements of the current flowing in the final feed.
Quantum firmware and the quantum computing stack
Authors: Ball Harrison , Biercuk Michael J. , Hush Michael R.
Published: March 2021

Integrated quantum-control protocols could bridge the gap between abstract algorithms and the physical manipulation of imperfect hardware.
Private health insurance reforms: impact of the psychiatric care waiting period exemption policy
Authors: Keating Catherine , Rowley Sarah , Wilson Andrew
Published: March 2021

Younger people are more likely to experience incident mental health conditions and hold lower levels of private health insurance coverage. Government reforms introduced in 2018 enabled customers to avoid 2-month waiting periods to access mental health hospital care. Effectiveness in reducing time to admission is assessed.
Efficacy of short-term cold storage prior to cryopreservation of spermatozoa in a threatened lizard
Authors: Campbell Lachlan , Clulow John , Howe Belinda , Upton Rose , Doody Sean , Clulow Simon
Published: March 2021

Assisted reproductive technologies (ARTs) have a significant role to play in reptile conservation, yet are severely lacking. Previous attempts to cryopreserve spermatozoa in the threatened lizard Varanus panoptes achieved approximately 48% motile sperm post-thaw for samples frozen immediately after collection. However, the feasibility of extended cold storage before cryopreservation has not been tested. We held V. panoptes spermatozoa at either 25°C or 4°C for 8 days, assessing sperm motility at days 1, 2, 4 and 8. Subsamples were cryopreserved on days 1 and 4 following the previously reported protocol for this species. Percentage motility decreased rapidly at 25°C, but did not decrease significantly until 4 days after collection at 4°C, with >30% motility maintained after 8 days. There was no significant difference in post-thaw motility or viability of samples cryopreserved after 1 or 4 days storage at 4°C, yielding substantial results for both parameters (mean motility 23.8% and 28.1% and mean viability 50.1% and 57.5% after 1 and 4 days respectively). We demonstrate the capacity to extend sperm viability for up to 8 days in unfrozen samples and to produce acceptable post-thaw motility in samples frozen after 4 days of storage, contributing to the development of valuable ARTs for lizards and other reptiles.
Do conversations end when people want them to?
Authors: Mastroianni Adam M. , Gilbert Daniel T. , Cooney Gus , Wilson Timothy D.
Published: March 2021

Significance

Social connection is essential to physical and psychological well-being, and conversation is the primary means by which it is achieved. And yet, scientists know little about it—about how it starts, how it unfolds, or how it ends. Our studies attempted to remedy this deficit, and their results were surprising: conversations almost never end when anyone wants them to! At a moment in history when billions of people have been forced to curtail their normal social activities and to reimagine this one, a scientific understanding of conversation could hardly be timelier.
ASCL2 reciprocally controls key trophoblast lineage decisions during hemochorial placenta development
Authors: Varberg Kaela M. , Iqbal Khursheed , Muto Masanaga , Simon Mikaela E. , Scott Regan L. , Kozai Keisuke , Choudhury Ruhul H. , Aplin John D. , Biswell Rebecca , Gibson Margaret , Okae Hiroaki , Arima Takahiro , Vivian Jay L. , Grundberg Elin , Soares Michael J.
Published: March 2021

Significance

Defective placentation, including impaired uterine spiral artery remodeling, leads to pregnancy disorders such as pregnancy loss, preeclampsia, intrauterine growth restriction, and preterm birth, all of which cause significant morbidity and mortality for the mother and fetus. Trophoblast cells are central to executing placental functions and can differentiate into two conserved specialized lineages: invasive/extravillous trophoblast cells, which guide uterine transformation, and syncytiotrophoblast, which serve a barrier function. We leveraged model systems to identify achaete-scute homolog 2 as a conserved regulator of the invasive/extravillous trophoblast cell lineage and a modulator of the syncytiotrophoblast phenotype. A key upstream regulator of trophoblast-engineered uterine transformation has been identified representing an entry point into the etiology of pregnancy complications resulting from defective placentation.
Simple stochastic model for geomagnetic excursions and reversals reproduces the temporal asymmetry of the axial dipole moment
Authors: Molina-Cardín Alberto , Dinis Luis , Osete María Luisa
Published: March 2021

Significance

The geodynamo, the process that produces and controls the evolution of the Earth’s magnetic field, is still not fully understood. Despite the success of current numerical geodynamo models in reproducing some geomagnetic observations, their high complexity and computational requirements hinder their use for certain studies. Here, we present a simple model based on random fluctuations that is able to reproduce the temporal asymmetry of the dipolar strength of the field observed during polarity reversals. This behavior arises due to the existence of two parts of the model that are energetically unbalanced, imposing a preferred direction of energy transfer, and we propose that the same mechanism would be the cause of the temporal asymmetry of the geodynamo.
SUMO enables substrate selectivity by mitogen-activated protein kinases to regulate immunity in plants
Authors: Verma Vivek , Srivastava Anjil K. , Gough Catherine , Campanaro Alberto , Srivastava Moumita , Morrell Rebecca , Joyce Joshua , Bailey Mark , Zhang Cunjin , Krysan Patrick J. , Sadanandom Ari
Published: March 2021

Significance

The functional diversity of MAPKs is dependent on differential selection of substrates for phosphorylation. Nevertheless, the mechanisms assisting MAPKs to maintain substrate specificity in plants are not known. Our study shows that WRKY33, a pathogen-responsive MPK3/6 substrate, is SUMOylated in response to pathogen-associated molecular patterns and pathogen signals. SUMOylation mediates WRKY33 phosphorylation and its activation. This correlation is reliant on the selective identification of SUMOylated WRKY33 by MPK3/6 via SUMO interaction motif (SIM) sites. Therefore, WRKY33 SUMOylation is important to selectively interact with MAPKs via the SUMO–SIM module and undergo phosphorylation and thus activation. Our data reveal a mechanism by which MPK3/6 prioritize molecular pathways by differentially selecting substrates using the SUMO–SIM module.
mTORC1-chaperonin CCT signaling regulates m
6
A RNA methylation to suppress autophagy
Authors: Tang Hong-Wen , Weng Jui-Hsia , Lee Wen Xing , Hu Yanhui , Gu Lei , Cho Sungyun , Lee Gina , Binari Richard , Li Cathleen , Cheng Min En , Kim Ah-Ram , Xu Jun , Shen Zhangfei , Xu Chiwei , Asara John M. , Blenis John , Perrimon Norbert
Published: March 2021

Significance

N6-methyladenosine (m
6
A) is the most prevalent modification in eukaryotic messenger RNA (mRNA) and affects RNA metabolism including splicing, stability, and translation. The m
6
A methyltransferase complex (MTC) is responsible for generating the m
6
A modifications in mRNA; however, the regulation of m
6
A modification is still unclear. We have identified Mechanistic Target of Rapamycin Complex 1 (mTORC1) as a key regulator of MTC and demonstrate that mTORC1 can stabilize MTC via activation of the chaperonin CCT complex and upregulate m
6
A modification to promote the degradation of ATG transcripts. Thus, our study unveils an mTORC1-signaling cascade that regulates m
6
A RNA methylation and autophagy.
A versatile platform for locus-scale genome rewriting and verification
Authors: Brosh Ran , Laurent Jon M. , Ordoñez Raquel , Huang Emily , Hogan Megan S. , Hitchcock Angela M. , Mitchell Leslie A. , Pinglay Sudarshan , Cadley John A. , Luther Raven D. , Truong David M. , Boeke Jef D. , Maurano Matthew T.
Published: March 2021

Significance

Functional analysis of noncoding genomic regulatory elements, which harbor the majority of common human disease and trait associations, is complicated by their cellular and genomic context sensitivity. We developed Big-IN, a method for rewriting large segments of mammalian genomes, including full genes and their surrounding regulatory elements. We demonstrate a flexible genomic verification pipeline to identify correctly engineered cells. We expect Big-IN will enable technologies for synthesis and assembly of large DNAs to catalyze a synthetic approach to regulatory genomics.
Child heritage speakers’ production and comprehension of direct object clitic gender in Spanish
Authors: Shin Naomi , Rodríguez Barbara , Armijo Aja , Perara-Lunde Molly
Published: March 2021

This study investigates 37 child heritage speakers’ direct object (DO) clitics in Spanish. Results from a
production task show that DO expression versus omission was related to Spanish vocabulary: the lower the vocabulary score, the
more omitted DOs. In contrast, DO clitic gender was related to English: children who used more English in the home and who had
higher English vocabulary scores produced more gender mismatches, most notably lo referring to feminine
referents. Results from a comprehension task suggest that children do not attend to clitic gender for referent identification.
We argue that the disambiguation function of DO clitic gender, which is infrequent in discourse, may take a long time to
develop. Overall, the study suggests that the extent to which restricted input and crosslinguistic influence affect child
heritage speakers’ minority language grammar may be mediated by the nature of the linguistic phenomenon in question.
Adjective-noun order in Papiamento-Dutch code-switching
Authors: Pablos Leticia , Parafita Couto M. Carmen , Boutonnet Bastien , de Jong Amy , Perquin Marlou , de Haan Annelies , Schiller Niels O.
Published: March 2021

In Papiamento-Dutch bilingual speech, the nominal construction is a potential ‘conflict site’ if there is
an adjective from one language and a noun from the other. Adjective position is pre-nominal in Dutch (cf. rode
wijn ‘red wine’) but post-nominal in Papiamento (cf. biña kòrá ‘wine red’). We test predictions
concerning the mechanisms underpinning word order in noun-adjective switches derived from three accounts: (i) the adjective
determines word order (Cantone & MacSwan, 2009), (ii) the matrix language
determines word order (Myers-Scotton, 1993, 2002), and (iii) either order is possible (Di Sciullo,
2014). An analysis of spontaneous Papiamento-Dutch code-switching production (Parafita Couto & Gullberg, 2017) could not distinguish between these predictions. We used
event-related brain potentials (ERPs) to measure online comprehension of code-switched utterances. We discuss how our results
inform the three theoretical accounts and we relate them to syntactic coactivation and the production-comprehension link.
OKAY in responding and claiming understanding
Authors: Betz Emma , Deppermann Arnulf
Published: March 2021

OKAY originates from English, but it is
increasingly used across languages. This chapter presents data from
13 languages, illustrating the spectrum of possible uses of OKAY in
responding and claiming understanding in contexts of informings.
Drawing on a wide range of interaction types from both informal and
institutional contexts, including those crucially involving embodied
practices, we show how OKAY can be used to (i) claim sufficient
understanding, (ii) mark understanding of the prior informing as
preliminary or not complete, and (iii) index discrepancy of
expectation.
OKAY in closings and transitions
Authors: Mondada Lorenza , Sorjonen Marja-Leena
Published: March 2021

This chapter discusses OKAY in transitions and
closings, based on findings in the data from 13 languages that are
analyzed in the project on OKAY. The chapter shows that OKAY
features in a variety of languages in closing environments at
different levels of organization, where the particle might occupy
diverse positions and do similar but also complementary work across
the languages. The sequential and activity environments to be
discussed include (i) sequence closings, (ii) activity closings,
(iii) transitions between activities or topics, and iv) the closing
of an entire conversation.
The prosody and phonetics of OKAY in American English
Authors: Couper-Kuhlen Elizabeth
Published: March 2021

This chapter is devoted to a study of the
prosodic and phonetic realization of the particle OKAY as deployed
in American English mundane conversation. Its primary aim is to
explore the question of whether there are recurrent
prosodic-phonetic formats associated with positionally distinct uses
of OKAY. The data come from telephone and face-to-face interactions
between family and friends spanning a period from the 1960s to the
present. Currently there are approximately 200 tokens in the
collection. The older and more recent data sets are considered
separately in order to capture changes that have ensued over the
last fifty to sixty years.
Rising OKAY in third position in Danish
talk-in-interaction
Authors: Sørensen Søren Sandager , Steensig Jakob
Published: March 2021

Earlier investigations claim that there are two
OKAY types in Danish: okay1, with falling pitch,
occurring mainly in third position, indicating sufficient
understanding, and okay2, with rising pitch,
indicating so-far understanding and that a projected trajectory may
continue. We have examined 235 cases of OKAY used in contexts where
understanding is at issue, and it turns out that a substantial
number of okay2 tokens occur in
“okay1 environments,” that is, in third
position following answers to questions. Our analyses of these cases
reveal that in this environment, okay2 is used to
indicate (1) that the answer could or should be expanded, or (2)
that there are still unresolved matters that the answer did not deal
with in full.
OKAY as a response to informings in Finnish
Authors: Koivisto Aino , Sorjonen Marja-Leena
Published: March 2021

This chapter examines the use of the particle
OKAY in Finnish as a response to turns that are designed to provide
new information. The study focuses on the ways in which the speakers
of OKAY orient toward the epistemic character of the informing, and
on its sufficiency for the purposes of the ongoing interaction.
These aspects are analyzed by paying attention to the sequential and
activity context of the particle, its phonetic-prosodic design, and
the possible subsequent talk in the turn. OKAY is also compared with
some other Finnish response particles in similar sequential and
activity contexts. The data come from telephone and face-to-face
interactions between family and friends spanning a period from the
late 1980s to the present.
Energy of cosmological spacetimes and perturbations: a quasilocal approach
*
Authors: Oltean Marius , Moghaddam Hossein Bazrafshan , Epp Richard J
Published: March 2021

Quasilocal definitions of stress–energy–momentum—that is, in the form of boundary densities (rather than local volume densities)—have proven generally very useful in formulating and applying conservation laws in general relativity. In this paper, we present a detailed application of such definitions to cosmology, specifically using the Brown–York quasilocal stress–energy–momentum tensor for matter and gravity combined. We compute this tensor, focusing on the energy and its associated conservation law, for FLRW spacetimes with no pertubrations and with scalar cosmological perturbations. For unperturbed FLRW spacetimes, we emphasize the importance of the vacuum energy (for both flat and curved space), which is almost universally underappreciated (and usually ‘subtracted’), and discuss the quasilocal interpretation of the cosmological constant. For the perturbed FLRW spacetime, we show how our results recover or relate to the more typical effective local treatment of energy in cosmology, with a view toward better studying the issues of the cosmological constant and of cosmological back-reactions.
Water-based resistive switches for neuromorphic long-range connections
Authors: Ananthakrishnan Akshay , Du Xingyu , Allen Mark G
Published: March 2021

The brain’s small-world network utilizes its short-range and long-range synaptic connections to process information in a complex and energy-efficient manner. To emulate the former, neuromorphic hardware typically leverages the conductance switching properties of thin-film dielectrics and semiconductors. Because these materials offer low ion mobilities, long-range connections built from thicker dielectrics require impractically-large forming voltages. To overcome this intrinsic shortcoming of solid-state active media, we present in this paper a simple Ag–H2O–Au cell that takes advantage of the relatively high ion mobility offered by deionized water to enable programmable connectivity switches between neurons separated by large gaps (∼40 µm). We introduce dual voltage programming schemes that allow the switch conductance to be modulated in analog and digital steps. When operating in the analog mode, the switch conductance could be potentiated and depressed over a relatively large (3.5×) range. In the digital mode, the Ag–H2O–Au switch delivered a high ON/OFF current ratio of ∼600 and sustained this margin over 200 switching cycles. Additionally, both switch states could be maintained for at least 3 h without external power. We show that unlike their solid-state counterparts, the water-gap in the Ag–H2O–Au cell can be easily refreshed without compromising the switching functionality. These attributes of Ag–H2O–Au switches in addition to their biocompatibility and simple design make them attractive for neuromorphic wetware implementations.
Nitrogen induced localised-state ensemble effect on multi quantum well GaInNAs with low indium concentration
Authors: Nordin M S , Samad M I A , Sarcan F , Mohamad K A , Alias A , Vickers A J
Published: March 2021

In this paper, temperature dependence photoluminescence has been taken on two multi-quantum well GaInNAs, with low indium composition and the impact of percentage nitrogen incorporation ⩽1%. The variation of peak energy position, linewidth, and integrated intensity emission have been investigated by adopting a localised state ensemble model to anticipate the dissimilar spontaneous emission mechanisms of the two samples. A good agreement has been observed between theoretical analysis and experimental data and enriches the understanding of the design and provides improvement opportunities for future GaInNAs based optoelectronic devices for biomedical applications.
Tuning of multi-magnetic phase and exchange bias effect by antisite disorder in Ca-doped La2CoMnO6 double perovskites
Authors: Sahoo R C , Das Sananda , Daw Debottam , Singh Ripandeep , Das A , Nath T K
Published: March 2021

The exchange bias effect at the magnetic interfaces and multi-magnetic phases strongly depends on the antisite disorder (ASD) driven spin configuration in the double perovskite systems. The percentage of ASD in double perovskites is extensively accepted as a key for designing diverse new nanospintronics with tailored functionalities. In this regards, we have investigated such ASD driven phenomena in Ca2+ doped bulk and polycrystalline La2−x
Ca
x
CoMnO6 (0 ⩽ x ⩽ 1) series of samples. The structural and Raman studies provide evidence of an increase in the disorder due to the increment of Ca concentration in the parent compound (x = 0). The enhancement of disorder in the doped system induces various magnetic orderings, magnetic frustration and cluster glass-like behavior, which have been confirmed from AC and DC magnetic studies and neutron diffraction studies. As a result, significantly large exchange bias effects, namely zero-field cooled (spontaneous) and field-cooled (conventional) exchange bias, are found. These results reveal the tuning of ASD by doping, which plays an active role in the spin configuration at the magnetic interfaces.
Laminated polyacrylonitrile nanofiber membrane codoped with boehmite nanoparticles for efficient electrostatic capture of particulate matters
Authors: Zhang Han , Zhang Xiaowei , Wang Pengjun , Chen Ruowang , Gu Gangwei , Hu Shiqian , Tian Ruoyu
Published: March 2021

Particulate matters (PMs) air pollution is identified as the major threat to public health and climate. High-performance air filter technology based on various electrospun nanofibers is considered as an effective strategy to eliminate the effects of PMs air pollution. However, to date, nearly all the existing micro-/nanofibers are hard to meet both requirements of high PMs removal efficiency and long service life. In this work, we reported the production of laminated polyacrylonitrile(PAN)-boehmite nanoparticles (BNPs) nanofiber structured membrane by the electrospinning process. The dimension of PAN-BNPs nanofiber can be tunable from (0.09 ± 0.03) μm to (0.81 ± 0.11) μm by controlling the PAN and BNPs concentrations in precursors. The optimized PAN-BNPs nanofiber air filter with a basis weight of 1 g m−2 demonstrates the attractive attributes of high PM2.5 removal efficiency up to 99.962% and low pressure drop of 58 Pa. Most importantly, after introducing the BNPs as electret, the removal efficiency is very stable under the air flow rate of 6 l min−1. This PAN-BNPs nanofiber with a long electrostatic duration time offers an approach for fabricating future high-performance air filters.
Bayesian uncertainty quantification for magnetic resonance fingerprinting
Authors: Metzner Selma , Wübbeler Gerd , Flassbeck Sebastian , Gatefait Constance , Kolbitsch Christoph , Elster Clemens
Published: March 2021

Magnetic Resonance Fingerprinting (MRF) is a promising technique for fast quantitative imaging of human tissue. In general, MRF is based on a sequence of highly undersampled MR images which are analyzed with a pre-computed dictionary. MRF provides valuable diagnostic parameters such as the T
1 and T
2 MR relaxation times. However, uncertainty characterization of dictionary-based MRF estimates for T
1 and T
2 has not been achieved so far, which makes it challenging to assess if observed differences in these estimates are significant and may indicate pathological changes of the underlying tissue. We propose a Bayesian approach for the uncertainty quantification of dictionary-based MRF which leads to probability distributions for T
1 and T
2 in every voxel. The distributions can be used to make probability statements about the relaxation times, and to assign uncertainties to their dictionary-based MRF estimates. All uncertainty calculations are based on the pre-computed dictionary and the observed sequence of undersampled MR images, and they can be calculated in short time. The approach is explored by analyzing MRF measurements of a phantom consisting of several tubes across which MR relaxation times are constant. The proposed uncertainty quantification is quantitatively consistent with the observed within-tube variability of estimated relaxation times. Furthermore, calculated uncertainties are shown to characterize well observed differences between the MRF estimates and the results obtained from high-accurate reference measurements. These findings indicate that a reliable uncertainty quantification is achieved. We also present results for simulated MRF data and an uncertainty quantification for an in vivo MRF measurement. MATLAB® source code implementing the proposed approach is made available.
Influence of lipid rafts on pattern formation during T-cell adhesion
Authors: Li Long , Hu Jinglei , Różycki Bartosz , Wang Xiaohuan , Wu Helong , Song Fan
Published: March 2021

Adhesion of T cells to antigen presenting cells is mediated by the TCR–MHCp and LFA1–ICAM1 protein complexes. These intercellular protein complexes segregate and form characteristic special patterns in the cell contact zone. Previous studies have attempted to explain the mechanisms of formation of these patterns. While emphasis has been put on membrane elasticity and active cytoskeletal transport, it remains unclear whether and how the pattern formation process is related to lipid rafts, which are nanoscale molecular clusters enriched in cholesterol and saturated phospholipids in cell membranes. Using Monte Carlo simulations of a statistical mechanical model for T-cell adhesion, we find that lipid rafts can lead to the formation of intermediate pattern with a ring of LFA1–ICAM1 complexes around a central domain of TCR–MHCp complexes even in the absence of active transport of T-cell receptor (TCR) molecules toward the center of the contact zone. In the presence of active TCR transport, lipid rafts can accelerate the formation of this monocentric pattern. We also find that lipid rafts have a strong stabilizing effect on the monocentric pattern after removal of the active TCR transport. Our results not only help to explain recent experimental observations, but also demonstrate that lipid rafts can cooperate with active cytoskeletal transport during the immunological synapse formation.
Advanced multivariate analysis methods for use by the experiments at the Large Hadron Collider*
Authors: Stakia Anna
Published: March 2021

In the course of the past four years, AMVA4NewPhysics, a Horizon2020-funded Marie Skłodowska-Curie (MSCA) Innovative Training Network, focused on the study of Multivariate Analysis Methods and Statistical Learning tools for the High Energy Physics research. Through the individual and collaborative work of its members, AMVA4NewPhysics succeeded in developing and optimising several such tools for use by the ATLAS and CMS experiments at the Large Hadron Collider, at CERN, promising to improve their measurement and search sensitivity. In this paper, some of these new tools are presented, along with their related results.
Single-channel vector magnetic information detection method based on diamond NV color center*
Authors: Wang Qin-Qin , Wang Rui-Rong , Liu Jin-Ping , Lin Shao-Zhuo , Wu Liang-Wei , Guo Hao , Li Zhong-Hao , Wen Huan-Fei , Tang Jun , Ma Zong-Min , Liu Jun
Published: March 2021

A method of detecting the single channel triaxial magnetic field information based on diamond nitrogen-vacancy (NV) color center is introduced. Firstly, the incident angle of the bias magnetic field which can achieve the equal frequency difference optically-detected magnetic resonance (ODMR) spectrum of diamond NV color center is calculated theoretically, and the triaxial magnetic information solution model is also constructed. Secondly, the microwave time-controlled circuit module is designed to generate equal timing and equal frequency difference microwave pulse signals in one channel. Combining with the optical detection magnetic resonance technology, the purpose of sequentially locking and detecting the four formant signals on one side of the diamond NV color center (m
s = –1 state signal) is achieved, and the vector magnetic field information detection is accomplished by combining the triaxial magnetic information solution model. The system can obtain magnetic field detection in a range of 0 mT–0.82 mT. The system’s magnetic noise sensitivity is 14.2 nT/Hz1/2, and the deviation angle errors of magnetic field detection θx
and θy
are 1.3° and 8.2° respectively.
High speed ghost imaging based on a heuristic algorithm and deep learning*
Authors: Huang Yi-Yi , Ou-Yang Chen , Fang Ke , Dong Yu-Feng , Zhang Jie , Chen Li-Ming , Wu Ling-An
Published: March 2021

We report an overlapping sampling scheme to accelerate computational ghost imaging for imaging moving targets, based on reordering a set of Hadamard modulation matrices by means of a heuristic algorithm. The new condensed overlapped matrices are then designed to shorten and optimize encoding of the overlapped patterns, which are shown to be much superior to the random matrices. In addition, we apply deep learning to image the target, and use the signal acquired by the bucket detector and corresponding real image to train the neural network. Detailed comparisons show that our new method can improve the imaging speed by as much as an order of magnitude, and improve the image quality as well.
Balancing Excitation and Inhibition of Spike Neuron Using Deep Q Network (DQN)
Authors: Szi Hui Tan , Khairi Ishak Mohamad , Fauzi Packeer Mohamed Mohamed , Mohd Fadzil Lokman , Afif Ahmarofi Ahmad
Published: March 2021

Deep reinforcement learning which involved reinforcement learning with artificial neural networks allows an agent to take the best possible actions in a virtual environment to achieve goals. Spike neuron has a non-differentiable spike generation function that caused SNN training faced difficulty. In order to overcome the difficulty, Deep Q Network (DQN) is proposed to act as an agent to interact with a custom environment. A spike neuron is modelled by using NEST simulator. Rewards are given to the agent for every action taken. The model is trained and tested to validate the performance of the trained model in order to attain balance the firing rate of excitatory and inhibitory population of spike neuron. Training result showed the agent able to handle the environment. The trained model capable to balance the excitation and inhibition of the spike neuron as the actual output neuron rate is close to or same with the target neuron firing rate. The average percentage error of rate of difference between output and target neuron rate for 5 episodes achieved 0.80%.
Utilization of Gravitational Search Algorithm for Combinatorial T-Way Testing
Authors: Maung Htay Khin , Razif Othman Rozmie , Amir Amiza
Published: March 2021

Different techniques of software testing are adopted to deal with bugs found in the highly complicated multifunctional software. However, those techniques have difficulty detecting bugs effectively because most of the bugs are triggered by interaction failures between the input parameters and values in the system. Thus, combinatorial t-way testing strategies have come into existence to produce quality minimized test cases, as well as those test cases can cover all the necessary interactions of parameters once at the least. Besides, as t-way testing is considered as an NP-hard problem, new strategies are always welcomed in this research area in pursuit of the optimum test suite. The main point of this paper is to propose the concept of a type of artificial intelligence (AI) algorithm called gravitational search algorithm (GSA) for t-way interaction testing. GSA is a stochastic optimization algorithm inspired by Newton’s law of gravity and motion and has been widely applied to figure out optimal solutions to real-world issues.
“LOOK & BLINK” TWO STEP VERIFICATION SECURITY LOG IN SYSTEM
Authors: Kai Qi Liang , Hussin Razaidi , Kamarudin Afzan , Che Ismail Rizalafande , Nazrin Md Isa Mohd , Zarina Md Naziri Siti
Published: March 2021

A new artificial intelligence security design which is face recognition with eye blinking login system is proposed. It aims to strengthen the security account for each user using artificial intelligence technology and increase speed and user convenience for security during login. The face of a person cannot be copied and it can replace the username of the user, while eye blinking detection is another step for double verification replacing the password of a user. It is a two-step verification process that can be applied to all sorts of account login field so that this technology can replace the old school username with a password security system. The recognition system used a real-time where it is reducing the number of hackers in the field as it is impossible to hack a person’s real-time face. The proposed system has been tested and analyzed the functionality by accessing the personal account in the university’s portal.
A Study and Analysis of High Efficiency CMOS Power Amplifier for IoT Applications
Authors: Siang Yi Koh , Anuar Zainol Murad Sohiful , Mohyar S N
Published: March 2021

This paper presents a study and analysis of high efficiency CMOS power amplifier (PA) for Internet of Thing (IoT) application. The studied mainly focused on the topology employed in designing high efficiency PA in gigahertz range frequencies. This study covers the basic class-E PA and the topologies in designing class-E PA such as single-stage, two-stage, multistage and differential. The circuits structure and the performances of class-E PA is discussed. The analysis is focusing on the efficiency of the proposed PA. The latest CMOS PAs developments have been studied and a summarization of the performance specification for different topologies are elaborated.
Data Security Implementation using Data Encryption Standard Method for Student Values at the Faculty of Medicine, University of North Sumatra
Authors: Ikhwan Ali , Raof Rafikha Aliana A. , Ehkan Phaklen , Yacob Yasmin , Syaifuddin M.
Published: March 2021

It is undeniable that advances in technology and the rapid spread of information are also accompanied by an increase of crime in the IT field, very valuable information is sought by criminals in the IT field in order to be misused so that they gain enormous profits. One of the information is student value data, so a system is needed that applies a cryptographic algorithm that can secure the information in this case the method used is securing student value data using the Data Encryption Standard (DES) algorithm. DES is asymmetrical cryptographic algorithm and is also classified as a cipher block with a 64-bit key size. DES converts plaintext into a ciphertext of the same size, 64 bits using a 56-bit internal key. By building a system to implement the DES algorithm in securing data values, it is hoped that it can help the Faculty of Medicine, University of North Sumatra in protecting the confidentiality of data values from irresponsible parties