Browse Articles

Embracing plant plasticity or robustness as a means of ensuring food security

Voltage controlled light states in a spatially pseudo-random bit sequence encoded optical lattice

We have demonstrated reconfigurable light states in an optical lattice utilizing the electro-optic Pockels effect in a LiNbO3 slab through altering the transverse refractive index profile of the lattice by pseudo-random bit sequence (PRBS). By modifying the PRBS equivalent voltage range, different light states (ballistic, superdiffusive, diffusive, subdiffusive, and localized) are achieved within the completely disordered lattice. Furthermore, altering the maximum length size and number of periods of the PRBS creates lattices with different pseudo-random refractive index patterns. This provides a broader range of voltage control for switching from superdiffusive state to diffusive state than completely disorder lattice, allowing for precise voltage control over spatial profile for specific applications. This reconfigurable light states in this PRBS controlled lattice hold significant promise for various uses within a single integrated platform even after fabrication.

Rapid detection of drug abuse via tear analysis using surface enhanced Raman spectroscopy and machine learning

Inferring effects of mutations on SARS-CoV-2 transmission from genomic surveillance data

AbstractNew and more transmissible variants of SARS-CoV-2 have arisen multiple times over the course of the pandemic. Rapidly identifying mutations that affect transmission could improve our understanding of viral biology and highlight new variants that warrant further study. Here we develop a generic, analytical epidemiological model to infer the transmission effects of mutations from genomic surveillance data. Applying our model to SARS-CoV-2 data across many regions, we find multiple mutations that substantially affect the transmission rate, both within and outside the Spike protein. The mutations that we infer to have the largest effects on transmission are strongly supported by experimental evidence from prior studies. Importantly, our model detects lineages with increased transmission even at low frequencies. As an example, we infer significant transmission advantages for the Alpha, Delta, and Omicron variants shortly after their appearances in regional data, when they comprised only around 1-2% of sample sequences. Our model thus facilitates the rapid identification of variants and mutations that affect transmission from genomic surveillance data.

Tuning the superconducting dome in granular aluminum thin films

The peculiar superconducting properties of granular aluminum, which consists of nanometer-sized aluminum grains separated by aluminum oxide, are attractive for applications in quantum circuitry, and they are interesting from a fundamental materials physics view. The phase diagram of granular aluminum as a function of normal-state resistivity features a superconducting dome with a maximum critical temperature Tc well above the Tc=1.2K of pure aluminum. Here, we show how the maximum Tc of this superconducting dome grows if the substrate temperature during deposition is lowered from 300 K to cooling with liquid nitrogen (150 and 100 K) and liquid helium (25 K). The highest Tc that we observe is 3.27 K. These results highlight that granular aluminum is a model system for complex phase diagrams of superconductors and demonstrate its potential in the context of high kinetic inductance applications. This is augmented by our observation of comparably sharp superconducting transitions of high-resistivity samples grown at cryogenic temperatures and by a thickness dependence even for films substantially thicker than the grain size.

Genomic evidence of improved fertility and adaptation in Iranian domestic sheep attributed to introgression from Asiatic Mouflon and urial

Dentate gyrus norepinephrine ramping facilitates aversive contextual processing

Microtubules Sequester Acetylated YAP in the Cytoplasm and Inhibit Heart Regeneration

BACKGROUND: The Hippo pathway effector YAP (Yes-associated protein) plays an essential role in cardiomyocyte proliferation and heart regeneration. In response to physiological changes, YAP moves in and out of the nucleus. The pathophysiological mechanisms regulating YAP subcellular localization after myocardial infarction remain poorly defined. METHODS: We identified YAP acetylation at site K265 by in vitro acetylation followed by mass spectrometry analysis. We used adeno-associated virus to express YAP-containing mutations that either abolished acetylation (YAP-K265R) or mimicked acetylation (YAP-K265Q) and studied how acetylation regulates YAP subcellular localization in mouse hearts. We generated a cell line with YAP-K265R mutation and investigated the protein-protein interactors by YAP immunoprecipitation followed by mass spectrometry, then validated the YAP interaction in neonatal rat ventricular myocytes. We examined colocalization of YAP and TUBA4A (tubulin α 4A) by superresolution imaging. Furthermore, we developed YAP-K265R and αMHC-MerCreMer (MCM); Yap-loxP/K265R mutant mice to examine the pathophysiological role of YAP acetylation in cardiomyocytes during cardiac regeneration. RESULTS: We found that YAP is acetylated at K265 by CBP (CREB-binding protein)/P300 (E1A-binding protein P300) and is deacetylated by nicotinamide phosphoribosyltransferase/nicotinamide adenine dinucleotide/sirtuins axis in cardiomyocytes. After myocardial infarction, YAP acetylation is increased, which promotes YAP cytoplasmic localization. Compared with controls, mice that were genetically engineered to express a K265R mutation that prevents YAP K265 acetylation showed improved cardiac regenerative ability and increased YAP nuclear localization. Mechanistically, YAP acetylation facilitates its interaction with TUBA4A, a component of the microtubule network that sequesters acetylated YAP in the cytoplasm. After myocardial infarction, the microtubule network increased in cardiomyocytes, resulting in the accumulation of YAP in the cytoplasm. CONCLUSIONS: After myocardial infarction, decreased sirtuin activity enriches YAP acetylation at K265. The growing TUBA4A network sequesters acetylated YAP within the cytoplasm, which is detrimental to cardiac regeneration.

Temperature-independent zero–zero-birefringence polymer using <i>N</i>-substituted maleimide and styrene

To date, the orientational birefringence and the photoelastic birefringence of alternating copolymers have not been studied in detail. We focused on N-substituted maleimide (RMI) and styrene (St) as alternating copolymers and analyzed the birefringence, refractive index, and glass transition temperature (Tg) of the alternating copolymers. It was found that the photoelastic coefficient and Tg exhibit a nonlinear relationship with the composition ratio of RMI and St. It is considered that the alternating copolymerization of RMI and St confirms that the conformation is inhibited by interacting with each other. A zero–zero-birefringence polymer that exhibits no birefringence was obtained by using N-ethylmaleimide and St and adjusting the composition ratio. This polymer showed a high Tg, low haze, and a low temperature dependence of birefringence.

Different temperatures leakage mechanisms of (Al2O3)x(HfO2)1−x gate Dielectrics deposited by atomic layer deposition

BrCF2CN for photocatalytic cyanodifluoromethylation

40th Anniversary of the TIMI Study Group

Experimental observation of mutual coupling in resonator array on thin-metal-film

We present the experimental observation of electromagnetic mutual coupling in an array of ring-shaped resonators (meta-atoms) fabricated on a free-standing thin metal film using a maskless direct laser ablation technique. The transmission spectra of various resonator configurations were measured via terahertz time-domain spectroscopy and a vector network analysis. Numerical modeling of periodically arranged resonators, employing multipole decomposition, revealed a clear dependence of inter-element coupling on the number of meta-atoms in the array. Theoretical analysis of electric and magnetic dipoles and quadrupoles elucidates the nature of resonance peak splitting and broadening, resulting in a reduction in the quality factor as the number of meta-atoms increases. We anticipate that observed inter-element coupling behavior along with multipole mode analysis could advance the development of multi-pixel emitters, 2D plasmonic THz sources, sensors, electro-optical modulators, and resonators for subwavelength photonic and plasmonic applications.

Exploring the physiological, biochemical, and enzymatic responses of Vigna mungo varieties to Mungbean Yellow Mosaic India Virus (MYMIV) infection

Mitotic block and epigenetic repression underlie neurodevelopmental defects and neurobehavioral deficits in congenital heart disease

Spotlight on YAP: Unlocking New Insights to Overcome the Barriers to Heart Regeneration

Spin-transfer switching dynamics in a two-macrospin-coupled model system

A quantitative understanding of spin-torque switching of nanomagnets beyond a macrospin limit and at finite temperature is important for applications, such as spin-torque magnetic random access memory (STT-MRAM). Thermally activated switching of a nanomagnet under a sub-threshold spin-transfer-torque (STT) bias has long been used to measure the thermal-activation reversal energy barrier related to memory bit’s data retention lifetime. Finite temperature write-error-rate (WER) statistics in non-macrospin systems are critically important for STT-MRAM write operations. For both thermally activated reversal and for write-error, descriptions beyond macrospin are necessary, as the macrospin-based asymptotic expressions are inaccurate beyond ∼2X for realistic experiments—doing so could cause unreliable interpretation for measurements of thermal-activation probability and WER characteristics. This is because most practical spin-transfer-torque switched MTJs are not macrospins. Here, using a two-macrospin coupled model as the next simplest case-study beyond a single macrospin, we demonstrate some key features of STT-biased non-macrospin dynamics, both in a thermal-activation region and for super-threshold fast-switching WER, and illustrate some behavioral differences of a system with more than a single macrospin’s internal degrees of freedom. These exercises provide an understanding to the correlation of quantitative trending of device behavior with material parameters and help to guide further optimization of materials and device designs for switching and data retention for nanomagnets in memory related applications.

Multi-level clustering and Prediction based energy efficient routing protocol to eliminate Hotspot problem in Wireless Sensor Networks.

AbstractConserving energy of sensor nodes and ensuring balanced workloads among them are fundamental concerns in Wireless Sensor Network (WSN) design. Clustering strategies offer a promising avenue to minimize node energy consumption, thereby prolonging network lifespan. Nevertheless, numerous multi-hop routing protocols using clustering technique face the challenge of nodes nearer to the Base Station (BS) depleting their energy faster due to forwarding data from the entire network leading to premature node failure and network partitioning known as ‘hotspot problem’. The paper introduces an Energy-Efficient Mega-Cluster-Based Routing (EEMCR) protocol specially designed for expansive coverage area. The primary principle behind designing this protocol is to eliminate the hotspot problem and restrict the transmission range of nodes to the threshold distance defined by the radio energy model, thereby enhancing the overall network lifespan. The protocol adopts a centralized approach employing fixed clustering wherein the BS partitions the network into square-shaped clusters. The cluster size is determined by the threshold transmission range of the sensor radio energy model, guaranteeing that all network communication stays within this threshold distance. Four such clusters form a mega-cluster with a Mega-Cluster-Head (MCH) elected among the four Cluster Heads (CHs). The MCH role is evenly distributed among nodes of all four clusters in subsequent rounds for uniform distribution of its overhead. Implementing data aggregation at two levels (CH level as well as MCH level) leads to reduced data traffic and energy consumption throughout the network. Moreover, data collection by two data mules based on odd–even round number ensures balanced data traffic and energy distribution across the network. Analysis indicates that the proposed protocol effectively mitigates the hot-spot problem and reduces data transmission overhead of sensor nodes. In simulation, the proposed protocol on an average improves network life by 34.5%, 23.5%, 14.5% and 5.5% as compared to existing protocols FCEEC, DBSCAN, LPGCR and FBECS respectively for deployment of nodes between 600 to 1200. Also, approximately 46%, 32%, 21% and 14% of lesser sensor nodes are dead for proposed protocol in respective rounds as compared to existing protocols FCEEC, DBSCAN, LPGCR and FBECS respectively. Comparative evaluations demonstrate improved network lifetime when compared to equivalent recent routing protocols.

Stable antivortices in multiferroic ε-Fe2O3 with the coalescence of misaligned grains

AbstractAntivortices have potential applications in future nano-functional devices, yet the formation of isolated antivortices traditionally requires nanoscale dimensions and near-zero magnetocrystalline anisotropy, limiting their broader application. Here, we propose an approach to forming antivortices in multiferroic ε-Fe2O3 with the coalescence of misaligned grains. By leveraging misaligned crystal domains, the large magnetocrystalline anisotropy energy is counterbalanced, thereby stabilizing the ground state of the antivortex. This method overcomes the traditional difficulty of observing isolated antivortices in micron-sized samples. Stable isolated antivortices were observed in truncated triangular multiferroic ε-Fe2O3 polycrystals ranging from 2.9 to 16.7 µm. Furthermore, the unpredictability of the polarity of the core was utilized as a source of entropy for designing physically unclonable functions. Our findings expand the range of antivortex materials into the multiferroic perovskite oxides and provide a potential opportunity for ferroelectric polarization control of antivortices.

A Rare Noncoding Enhancer Variant in <i>SCN5A</i> Contributes to the High Prevalence of Brugada Syndrome in Thailand

BACKGROUND: Brugada syndrome (BrS) is a cardiac arrhythmia disorder that causes sudden death in young adults. Rare genetic variants in the SCN5A gene encoding the Na v 1.5 sodium channel and common noncoding variants at this locus are robustly associated with the condition. BrS is particularly prevalent in Southeast Asia but the underlying ancestry-specific factors remain largely unknown. METHODS: Genome sequencing of BrS probands and population-matched controls from Thailand was performed to identify rare noncoding variants at the SCN5A-SCN10A locus that were enriched in patients with BrS. A likely causal variant was prioritized by computational methods and introduced into human induced pluripotent stem cell (hiPSC) lines using CRISPR-Cas9. The effect of the variant on SCN5A expression and Na v 1.5 sodium channel current was then assessed in hiPSC-derived cardiomyocytes (hiPSC-CMs). RESULTS: A rare noncoding variant in an SCN5A intronic enhancer region was highly enriched in patients with BrS (detected in 3.9% of cases with a case-control odds ratio of 45.2). The variant affects a nucleotide conserved across all mammalian species and predicted to disrupt a Mef2 transcription factor binding site. Heterozygous introduction of the enhancer variant in hiPSC-CMs caused significantly reduced SCN5A expression from the variant-containing allele and a 30% reduction in Na v 1.5-mediated sodium current density compared with isogenic controls, confirming its pathogenicity. Patients with the variant had severe phenotypes, with 89% experiencing cardiac arrest. CONCLUSIONS: This is the first example of a functionally validated rare noncoding variant at the SCN5A locus and highlights how genome sequencing in understudied populations can identify novel disease mechanisms. The variant partly explains the increased prevalence of BrS in this region and enables the identification of at-risk variant carriers to reduce the burden of sudden cardiac death in Thailand.