BINA

We compare ergodic properties of the kinetic energy for three stochastic models of subrecoil-laser-cooled gases. One model is based on a heterogeneous random walk (HRW), another is an HRW with long-range jumps (the exponential model), and the other is a mean-field-like approximation of the exponential model (the deterministic model). All the models show an accumulation of the momentum at zero in the long-time limit, and a formal steady state cannot be normalized, i.e., there exists an infinite invariant density. We obtain the exact form of the infinite invariant density and the scaling function for the exponential and deterministic models and devise a useful approximation for the momentum distribution in the HRW model. While the models are kinetically non-identical, it is natural to wonder whether their ergodic properties share common traits, given that they are all described by an infinite invariant density. We show that the answer to this question depends on the type of observable under study. If the observable is integrable, the ergodic properties such as the statistical behavior of the time averages are universal as they are described by the Darling-Kac theorem. In contrast, for non-integrable observables, the models in general exhibit non-identical statistical laws. This implies that focusing on non-integrable observables, we discover non-universal features of the cooling process, that hopefully can lead to a better understanding of the particular model most suitable for a statistical description of the process. This result is expected to hold true for many other systems, beyond laser cooling.

How the splicing machinery defines exons or introns as the spliced unit has remained a puzzle for 30 years. Here, we demonstrate that peripheral and central regions of the nucleus harbor genes with two distinct exon-intron GC content architectures that differ in the splicing outcome. Genes with low GC content exons, flanked by long introns with lower GC content, are localized in the periphery, and the exons are defined as the spliced unit. Alternative splicing of these genes results in exon skipping. In contrast, the nuclear center contains genes with a high GC content in the exons and short flanking introns. Most splicing of these genes occurs via intron definition, and aberrant splicing leads to intron retention. We demonstrate that the nuclear periphery and center generate different environments for the regulation of alternative splicing and that two sets of splicing factors form discrete regulatory subnetworks for the two …

We present an experimental study of local magnetic imaging in order to visualize the current flow in superconducting networks. We track the evolution of the spatial distribution of the current flow as the network is driven from fully superconducting to fully normal phases. Our results highlight the factors that contribute to the disordered flow in superconducting networks during their collapse, and demonstrate that the current is never uniformly distributed in the network. These results can assist the design and development of circuits based on superconductors and Josephson junctions.

A conventional optical cavity supports modes which are confined because they are unable to leak out of the cavity. Bound state in continuum (BIC) cavities are an unconventional alternative, where light can leak out, but is confined by multimodal destructive interference. BICs are a general wave phenomenon, of particular interest to optics, but BICs and multimodal interference have never been demonstrated at the nanoscale. Here, we demonstrate the first nanophotonic cavities based on BIC-like multimodal interference. This novel confinement mechanism for deep sub-wavelength light shows orders of magnitude improvement in several confinement metrics. Specifically, we obtain cavity volumes below 100x100x3nm^ 3 with quality factors about 100, with extreme cases having 23x23x3nm^ 3 volumes or quality factors above 400. Key to our approach, is the use of pristine crystalline hyperbolic dispersion media …

Professor Shimon Vega (1943–2021) of the Weizmann Institute of Science passed away on the 16 th of November. Shimon Vega established theoretical frameworks to develop and explain solid-state nuclear magnetic resonance (NMR) and dynamic nuclear polarization (DNP) techniques and methodologies. His departure left a profound mark on his many students, postdocs, and colleagues. Shortly after his passing, we all assembled spontaneously for an international online meeting to share our reflections and memories of our experiences in Shimon’s lab and how they affected us deeply during that period of time and throughout our scientific careers. These thoughts and feelings were put here into writing.

Frequency-domain (FD) fluorometry is a widely utilized tool to probe unique features of complex biological structures, which may serve medical diagnostic purposes. The conventional data analysis approaches used today to extract the fluorescence intensity or fluorescence anisotropy (FA) decay data suffer from several drawbacks and are inherently limited by the characteristics and complexity of the decay models. This paper presents the squared distance (D^2) technique, which categorized samples based on the direct frequency response data (FRD) of the FA decay. As such, it improves the classification ability of the FD measurements of the FA decay as it avoids any distortion that results from the challenged translation into time domain data. This paper discusses the potential use of the D^2 approach to classify biological systems. Mathematical formulation of D^2 technique adjusted to the FRD of the FA decay is …

Optical imaging (OI) has become the most used alternative imaging tool for pre-clinical studies. Among all molecular imaging modalities, fluorescence optical imaging is central thanks to its high sensitivity, the numerous molecular probes available (either endogenous or exogenous) and its ability to simultaneously image multiple biomarkers or biological processes at various spatio-temporal scales. Especially, fluorescence lifetime imaging (FLI) has become an increasingly popular method, as it provides unique insights into the cellular micro-environment by non-invasively examining numerous intracellular parameters such as metabolic status, reactive oxygen species and intracellular pH. Moreover, FLI’s exploitation of native fluorescent signatures has been extensively investigated for enhanced diagnostic of numerous pathologies. However, to perform such measurements in intact, live specimen, it is required to …

A promising venue for hybrid quantum computation involves the strong coupling between impurity spins and superconducting circuits. This coupling can be controlled and enhanced by preparing superconducting resonators in nonclassical states, such as squeezed states. In this work, we theoretically study the effects of these states on the coherence properties of the spin. We develop an analytic approach based on the Schrieffer-Wolff transformation that allows us to quantitatively predict the dynamics of the spin, and we numerically confirm its validity. We find that squeezing can enhance the coupling between the resonator and the spin. However, at the same time, it amplifies the photon noise and enhances the spin decoherence. Our work demonstrates a major impediment in using squeezing to reach the strong-coupling limit.

Near-infrared (NIR) fluorescence lifetime imaging (FLI) provides a unique contrast mechanism to monitor biological parameters and molecular events in vivo. Single-photon avalanche diode (SPAD) cameras have been recently demonstrated in FLI microscopy (FLIM) applications, but their suitability for in vivo macroscopic FLI (MFLI) in deep tissues remains to be demonstrated. Herein, we report in vivo NIR MFLI measurement with SwissSPAD2, a large time-gated SPAD camera. We first benchmark its performance in well-controlled in vitro experiments, ranging from monitoring environmental effects on fluorescence lifetime, to quantifying Förster resonant energy transfer (FRET) between dyes. Next, we use it for in vivo studies of target-drug engagement in live and intact tumor xenografts using FRET. Information obtained with SwissSPAD2 was successfully compared to that obtained with a gated intensified charge-coupled device (ICCD) camera, using two different approaches. Our results demonstrate that SPAD cameras offer a powerful technology for in vivo preclinical applications in the NIR window.

Metasurfaces have seen a great evolution over the last few years, demonstrating a high degree of control over the amplitude, phase, polarization, and spectral properties of reflected or transmitted electromagnetic waves. Nevertheless, the inherent limitation of static metasurface realizations, which cannot be controlled after their fabrication, engages an ongoing pursuit for reconfigurable metasurfaces with profound tunability. In this paper, we mitigate this grand challenge by demonstrating a new method for free-space rapid optical tunability and modulation, utilizing a planar aluminum nanodisk metasurface coated with indium tin oxide (ITO) on a thin film of lithium niobate (LiNbO) with a chromium/gold (Cr/Au) substrate. Resonance coupling gives rise to an enhanced, confined electromagnetic field residing in the thin film, leading to a narrow and high contrast dip in reflectance of around 1.55 μm. The precise spectral …

Chemical element mapping is an imaging tool that provides essential information about composite materials, and it is crucial for a broad range of fields ranging from fundamental science to numerous applications. Methods that exploit x-ray fluorescence are very advantageous and are widely used, but require focusing of the input beam and raster scanning of the sample. Thus, the methods are slow and exhibit limited resolution due to focusing challenges. Here, we demonstrate an x-ray fluorescence method based on computational ghost imaging that overcomes those limitations since it does not require focusing and show that when it is combined with compressed sensing the total measurement time can be significantly reduced. Our method opens the possibility to significantly enhance the resolution of chemical element maps and to extend the applicability of x-ray fluorescence inspection to new fields where the …

Quantum entanglement and relativistic causality are key concepts in theoretical works seeking to unify quantum mechanics and gravity. In this article, a gedanken experiment that couples the spin to spacetime is proposed, and is then analyzed in the context of quantum information by using different approaches to quantum gravity. Both classical gravity theory and certain quantum theories predict that around a spin‐half particle, the spherical symmetry of spacetime is broken by its magnetic field or merely by its intrinsic angular momentum. It is asserted that any spin‐related deviation from spherical symmetry, upon appropriate measurement, can violate relativistic causality and quantum no‐cloning. To avoid these violations, the measurable spacetime around the particle's rest frame shall typically remain spherically symmetric, potentially as a back‐action by the act of a covariant measurement, or due to a quantized …

IntroductionDue to the increased use of CT and MRI, the prevalence of incidental findings on brain scans is increasing. Meningioma, the most common primary brain tumour, is a frequently encountered incidental finding, with an estimated prevalence of 3/1000. The management of incidental meningioma varies widely with active clinical-radiological monitoring being the most accepted method by clinicians. Duration of monitoring and time intervals for assessment, however, are not well defined. To this end, we have recently developed a statistical model of progression risk based on single-centre retrospective data. The model Incidental Meningioma: Prognostic Analysis Using Patient Comorbidity and MRI Tests (IMPACT) employs baseline clinical and imaging features to categorise the patient with an incidental meningioma into one of three risk groups: low, medium and high risk with a proposed active monitoring …

Research interest in the integration of solar energy-harvesting technology with bioenergy production is growing at a remarkable pace. The time of fruition of a completely off-grid solar-powered refinery facility is not too far, at least in the specific instance of bioenergy sources, namely, biodiesel and bioethanol. Electricity generated from solar panels is used for the cultivation of microalgae in outdoor open ponds. The solar thermal energy is converted into electricity by solar panels, and the electricity is stored in lead-acid batteries that are used to power the motors to rotate the agitator blades for stirring the contents of the algal culture. The biomass productivity of outdoor open ponds completely powered by solar energy (5.8 gm2/d of Nannochloropsis oceanica SCS-1981) is on par with the traditional raceway ponds. Such innovation in harvesting microalgae has led to energy savings and cost reduction. A solar energy …

Pharmaceutical nanoparticles (NPs) carrying molecular payloads are used for medical purposes such as diagnosis and medical treatment. They are designed to modify the pharmacokinetics-pharmacodynamics (PKPD) of their associated payloads, to obtain better clinical results. Currently, the research process of discovering the PKPD properties of new candidates for efficient clinical treatment is complicated and time-consuming. In silico experiments are known to be powerful tools for studying biological and clinical processes and therefore can significantly improve the process of developing new and optimizing current NPs-based drugs. However, the current PKPD models are limited by the number of parameters they can take into consideration and the ability to solve large-scale in vivo settings, thus providing relatively large errors in predicting treatment outcomes. In this study, we present a novel mathematical graph-based model for PKPD of NPs-based drugs. The proposed model is based on a population of NPs performing a directed walk on a graph describing the blood vessels and organs, taking into consideration the interactions between the NPs and their environment. In addition, we define a mechanism to perform different prediction queries on the proposed model to analyze two in vivo experiments with eight different NPs, done on mice, obtaining a fitting of 0.84 +- 0.01 and 0.66 +- 0.01 (mean +- standard deviation), respectively, comparing the in vivo values and the in silico results.

Functional surface coatings were applied on high voltage spinel (LiNi0.5Mn1.5O4; LNMO) and Ni-rich (LiNi0.85Co0.1Mn0.05O2; NCM851005) NCM cathode materials using few-layered 2H tungsten diselenide (WSe2). Simple liquid-phase mixing with WSe2 in 2-propanol and low-temperature (130 °C) heat treatment in nitrogen flow dramatically improved electrochemical performance, including stable cycling, high-rate performance, and lower voltage hysteresis in Li coin cells at 30 and 55 °C. Significantly improved capacity retention at 30 °C [Q401/Q9 of 99% vs 38% for LNMO and Q322/Q23 of 64% vs 46% for NCM851005] indicated efficient functionality. TEM and XPS clarified the coating distribution and coordination with the cathode surface, while postcycling studies revealed its sustainability, enabling lower transition metal dissolution and minor morphological deformation/microcrack formation. A modified and …

Carbon dots (CDs) are a novel type of carbon-based nanomaterial that has gained considerable attention for their unique optical properties, including tunable fluorescence, stability against photobleaching and photoblinking, and strong fluorescence, which is attributed to a large number of organic functional groups (amino groups, hydroxyl, ketonic, ester, and carboxyl groups, etc.). In addition, they also demonstrate high stability and electron mobility. This article reviews the topic of doped CDs with organic and inorganic atoms and molecules. Such doping leads to their functionalization to obtain desired physical and chemical properties for biomedical applications. We have mainly highlighted modification techniques, including doping, polymer capping, surface functionalization, nanocomposite and core-shell structures, which are aimed at their applications to the biomedical field, such as bioimaging, bio-sensor applications, neuron tissue engineering, drug delivery and cancer therapy. Finally, we discuss the key challenges to be addressed, the future directions of research, and the possibilities of a complete hybrid format of CD-based materials. View Full-Text

Solid matrix-supported liquid metal nanoparticles have been drawing attention as a nanoadditive in the fabrication of electroconductive flexible and soft materials. The present work reports a facile, green, and sonochemical synthesis approach of gallium (Ga) nanoparticles embedded in reduced graphene oxide (RGO) under ambient conditions for the first time. The as-synthesized ultrasonic energy-irradiated RGO/Ga nanocomposite was studied using SEM, TEM, DSC, XRD, XPS, and solid-state NMR. Because of their electrical conductivity, RGO/Ga nanoparticles have been used as a conducting inclusion for a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) matrix and coated on cotton fabrics to develop a smart e-textile for electromagnetic (EM) radiation-shielding application. In the X-band (8.2–12.4 GHz) frequency range, the nanocomposites’ EM interference-shielding efficiency was about …

Chemical element mapping is an imaging tool that provides essential information about composite materials, and it is crucial for a broad range of fields ranging from fundamental science to numerous applications. Methods that exploit x-ray fluorescence are very advantageous and are widely used, but require focusing of the input beam and raster scanning of the sample. Thus, the methods are slow and exhibit limited resolution due to focusing challenges. Here, we demonstrate an x-ray fluorescence method based on computational ghost imaging that overcomes those limitations since it does not require focusing and show that when it is combined with compressed sensing the total measurement time can be significantly reduced. Our method opens the possibility to significantly enhance the resolution of chemical element maps and to extend the applicability of x-ray fluorescence inspection to new fields where the …