Exact Modes Research Articles

Theory of Stimulated Brillouin Scattering in Fibers for Highly Multimode Excitations

Stimulated Brillouin scattering (SBS) is often an unwanted loss mechanism in both active and passive fibers. Highly multimode excitation of fibers has been proposed as a novel route toward efficient SBS suppression. Here, we develop a detailed, quantitative theory which confirms this proposal and elucidates the physical mechanisms involved. Starting from the vector optical and scalar acoustic equations, we derive appropriate nonlinear coupled mode equations for the signal and Stokes modal amplitudes and an analytical formula for the SBS (Stokes) gain with applicable approximations, such as the neglect of shear effects. This allows us to calculate the exponential growth rate of the Stokes power as a function of the distribution of power in a highly multimode signal. The peak value of the gain spectrum across the excited modes determines the SBS threshold—the maximum SBS-limited power that can be sent through the fiber. The theory shows that the peak SBS gain is greatly reduced by highly multimode excitation due to gain broadening and relatively weaker intermodal SBS gain. The inclusion of exact vector optical modes in the calculation is crucial in order to capture the incomplete intermodal coupling due to mismatch of polarization patterns of higher-order modes. We demonstrate that equal excitation of the 160 modes of a commercially available, highly multimode circular step index fiber raises the SBS threshold by a factor of 6.5 and find comparable suppression of SBS in similar fibers with a D-shaped cross section. Published by the American Physical Society 2024

Evaluation of in vitro antioxidant activities, total phenolic and elemental contents of common herbs and spices (Moringa oleifera leaves, Allium sativum (Garlic) and Momordica charantia (ejinrin) leaves) in South-West Nigeria

Abstract Natural remedies are being widely utilized in some disease’s conditions including cancer, diabetes, neurodegenerative diseases, atherosclerosis hypertension and other cardiovascular diseases. The therapeutic intervention of medicinal plants and spices cannot be overemphasized in the management and control of diseases but the exact modes of action of these herbs and plants have not been fully elucidated. This research work was designed to study the expression of selected elements, zinc (Zn), iron (Fe), copper (Cu), selenium (Se), lead (Pb) and cadmium (Cd); the phytochemical and the in vitro antioxidant properties of ethanolic extracts of Moringa oleifera leaves, Allium sativum (Garlic) and Momordica charantia (ejinrin) leaves for their potential involvement in the prevention and management of cardiovascular diseases and cancer through different chemical methods. In vitro antioxidant properties were assayed by investigating 2,2-diphenyl-2-picryl-hydrazyl (DPPH) free radicals scavenging potentials and Ferric Reducing Antioxidant Potential (FRAP); total phenolic content was determined by using Folin-Ciocalteu assay and the elemental contents of these extracts was investigated through the use of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). All tests were run in triplicates and analysed. Our results revealed that the ethanolic extracts of M. oleifera leaves, A. sativum (Garlic) and M. charantia (ejinrin) leaves possess significant antioxidant activities and express important and beneficial elements (in marginal and trace amounts) and phytochemicals. These results suggest that the medicinal attributes of these plants may be linked to the radical scavenging abilities, beneficial elements and phytochemicals expression of their ethanolic extracts which may likely be a good direction in the area of drug discovery and development.

Standard model and the lattice

The SU(3)⊗SU(2)⊗U(1) standard model maps smoothly onto a conventional lattice gauge formulation, including the parity violation of the weak interactions. The formulation makes use of the pseudoreality of the weak group and requires the inclusion a full generation of both leptons and quarks. As in continuum discussions, chiral eigenstates of the Dirac operator generate known anomalies, although with rough gauge configurations these are no longer exact zero modes of the Dirac operator. Published by the American Physical Society 2024

Metasurface for Engineering Superimposed Ince-Gaussian Beams.

Ince-Gaussian beams (IGBs) are the third complete family of exact and orthogonal solutions of the paraxial wave equation and have been applied in many fields ranging from particle trapping to quantum optics. IGBs play a very important role in optics as they represent the exact and continuous transition modes connecting Laguerre-Gaussian and Hermite-Gaussian beams. The method currently in use suffers from the high cost, complexity, and large volume of the optical system. The superposition of IGBs can generate complicated structured beams with multiple phase and polarization singularities. A metasurface approach is proposed to realizing various superpositions of IGBs without relying on a complicated optical setup. By superimposing IGBs with even and odd modes, multiple phase, and polarization singularities are observed in the resultant beams. The phase and polarization singularities are modulated by setting the initial phase in the design and controlling the incident linear polarization. The compactness of the developed metasurface devices and the unique properties of the generated beams have the potential to impact many practical applications such as particle manipulation, orbital angular momentum spectrum manipulation, and optical communications.

Implications of Hydrogen Sulfide in Epigenetic Controlling in Neurodegenerative Diseases: A Narrative Review

Previously we had we have reviewed various neurodegenerative diseases (NDD), inclusive of Alzheimer’s disease (AD), Parkinson’s disease (PD), as well as Huntington’s disease (HD), role of hydrogen sulfide (H2 S), in treatment of different cancers inclusive of breast cancer, glioma, hepatocellular carcinoma along with role of epigenetics in Diabetic Kidney Disease (DKD), as well as pregnancy. There by the objective of this review is provision of an exhaustive outline of the present research controlling epigenetic events correlated with NDD. Here we conducted a narrative review utilizing search engine pubmed, google scholar; web of science; embase; Cochrane review library utilizing the MeSH terms like neurodegenerative diseases (NDD); Alzheimer’s disease ; H2 S Parkinson’s disease; Huntington’s disease; hydrogen sulfide; Epigenetics; DNA methylation; Histone post-translational modifications; Histone protein acetylation; Histone methylation from 2000 till 2023 December till date. Emerging proof has initiated the unravelling of various facets by which H2 S impacts the epigenetic topography along with followed by the propagation of different NDD inclusive of AD, PD), as well as HD. H2 S possesses the capacity of modulating the crucial epigenetic machinery for instance DNA methylation, histone modifications along with noncoding RNAs influencing gene expression as well as cellular working germane to neuronal survival, neuroinflammation, as well as synaptic plasticity. Thus it is constructed how H2 S works in the form of an imperative actor amongst this close-knit network possessing the probability of opening innovative therapeutic arena. Although considerable work done, still lot of lacunae exist on the exact molecular modes plausible therapeutic repercussions of modulating the H2S quantities/its downstream targets. Finally isolation of future research directions having the objective of using the therapeutic capacity of H2 S in NDD.

Spinal GABA transporter 1 contributes to evoked-pain related behavior but not resting pain after incision injury.

The inhibitory function of GABA at the spinal level and its central modulation in the brain are essential for pain perception. However, in post-surgical pain, the exact mechanism and modes of action of GABAergic transmission have been poorly studied. This work aimed to investigate GABA synthesis and uptake in the incisional pain model in a time-dependent manner. Here, we combined assays for mechanical and heat stimuli-induced withdrawal reflexes with video-based assessments and assays for non-evoked (NEP, guarding of affected hind paw) and movement-evoked (MEP, gait pattern) pain-related behaviors in a plantar incision model in male rats to phenotype the effects of the inhibition of the GABA transporter (GAT-1), using a specific antagonist (NO711). Further, we determined the expression profile of spinal dorsal horn GAT-1 and glutamate decarboxylase 65/67 (GAD65/67) by protein expression analyses at four time points post-incision. Four hours after incision, we detected an evoked pain phenotype (mechanical, heat and movement), which transiently ameliorated dose-dependently following spinal inhibition of GAT-1. However, the NEP-phenotype was not affected. Four hours after incision, GAT-1 expression was significantly increased, whereas GAD67 expression was significantly reduced. Our data suggest that GAT-1 plays a role in balancing spinal GABAergic signaling in the spinal dorsal horn shortly after incision, resulting in the evoked pain phenotype. Increased GAT-1 expression leads to increased GABA uptake from the synaptic cleft and reduces tonic GABAergic inhibition at the post-synapse. Inhibition of GAT-1 transiently reversed this imbalance and ameliorated the evoked pain phenotype.

Analysis of guided optical eigenmodes in magneto-optical fibers with applications to OAM mode selective couplers

Mode division multiplexing technology can regard each eigenmode in optical fibers as an independent channel to carry different data information, helpful for improving the transmission capacity of optical fiber communication systems. The spatial distribution, state of polarization and propagation constant of guided optical eigenmodes in the magneto-optical fiber are derived theoretically by the analysis of linear polarization and exact modes. The transverse distribution of the eigenmodes in the MO fiber can be constructed by those of exact modes in the conventional fiber. The effect of applied magnetic field on the eigenmodes and their effective refractive indices is studied. Simulation results show that, the eigenmodes in the MO fiber may be represented by the pseudo-modes of circular polarization () or the true modes of orbital angular momentum () when applied magnetic field is sufficiently large. The measurement method for weak magnetic field based on Stokes parameters is proposed. The magnetic tunability of OAM mode selective couplers is also analyzed.

Computational tools for inferring transcription factor activity.

Transcription factors (TFs) are essential players in orchestrating the regulatory landscape in cells. Still, their exact modes of action and dependencies on other regulatory aspects remain elusive. Since TFs act cell type-specific and each TF has its own characteristics, untangling their regulatory interactions from an experimental point of view is laborious and convoluted. Thus, there is an ongoing development of computational tools that estimate transcription factor activity (TFA) from a variety of data modalities, either based on a mapping of TFs to their putative target genes or in a genome-wide, gene-unspecific fashion. These tools can help to gain insights into TF regulation and to prioritize candidates for experimental validation. We want to give an overview of available computational tools that estimate TFA, illustrate examples of their application, debate common result validation strategies, and discuss assumptions and concomitant limitations.

Complication rates and modes of short and medium-term failure in Motec total wrist arthroplasty: an international cohort study.

The aim of this study was to analyse the short- and medium-term complications of the Motec total wrist arthroplasty (TWA). Identifying exact modes of failure and their causes should allow surgeons to avoid or mitigate these risks in the future. Retrospective analysis of prospectively collected data from six hand surgeons at five international centres provided details of 171 Motec TWAs. The mean follow-up was 5.8 years (range 18 months to 12 years). There were 33 (19%) complications within our cohort, with a revision rate of 8.2% (14 revisions). There was no difference in complication rates between metal-on-metal and metal-on-polymer articulations. Failure of osseointegration was the most common complication. Problems with soft tissue balancing, implant impingement related osteolysis, bony impingement and metacarpal fracture were found to be other preventable causes of failure in this series. Elimination of these preventable complications will improve survival rates for this implant.Level of evidence: IV.

Comparison of a Telehealth-Based Intensive Treatment Program with a Rewarding App vs. On-Site Care for Youth with Obesity: A Historical Cohort Study.

The recommended treatment for children with obesity includes numerous consultations by a multidisciplinary team, which is very cumbersome. Telehealth can assist in administering frequent care to children with obesity, yet the exact approaches and modes of delivery are still explored. During the COVID-19 pandemic, we developed an intensive telehealth-based treatment program that included a rewarding app for children with obesity. The aim of this study was to compare 6-month changes in body mass index (BMI) and body fat percent between participants in the program (n = 70) vs. children that underwent historic on-site care (n = 87). After 6 months, more participants in the telehealth group continued treatment compared to the on-site group (79% vs. 60%, p < 0.001). A significant reduction in the median BMI z-score (zBMI) was seen after 6 months in both groups (p < 0.01), with a similar proportion of zBMI reductions (71% in the telehealth group, 75% in the comparison group, p = 0.76). No statistically significant differences were found between the study groups in 6-month changes in BMI, zBMI, body fat percent or fat z-scores. We conclude that our telehealth program, which was executed during the COVID-19 pandemic, resulted in a high proportion of children with zBMI reduction that was comparable with the more personal on-site care.

Backreaction issue for the black hole in de Sitter spacetime

We consider quantum real massive scalar field in the de Sitter-Schwarzschild space-time backround. To have an analytic head way we study in detail the two-dimensional case, assuming that the situation in four dimensions will not be much different conceptually. It is assumed, that quantum field is in a thermal state i.e. described by the planckian distribution for the exact modes in the geometry under consideration. We calculate approximately the expectation value of stress-energy tensor near the cosmological and black hole horizons. It is shown that for a generic temperature backreaction from quantum fields on the geometry cannot be neglected. Thus, de Sitter-Schwarzschild space-time geometry inevitably is strongly modified by the quantum fluctuations of the matter fields.

Non-linear Schrödinger equation with time-dependent balanced loss-gain and space–time modulated non-linear interaction

We consider a class of one dimensional vector Non-linear Schrödinger Equation (NLSE) in an external complex potential with Balanced Loss-Gain (BLG) and Linear Coupling (LC) among the components of the Schrödinger field. The solvability of the generic system is investigated for various combinations of time modulated LC and BLG terms, space–time dependent strength of the nonlinear interaction and complex potential. We use a non-unitary transformation followed by a reformulation of the differential equation in a new coordinate system to map the NLSE to solvable equations. Several physically motivated examples of exactly solvable systems are presented for various combinations of LC and BLG, external complex potential and nonlinear interaction. Exact localized nonlinear modes with spatially constant phase may be obtained for any real potential for which the corresponding linear Schrödinger equation is solvable. A method based on supersymmetric quantum mechanics is devised to construct exact localized nonlinear modes for a class of complex potentials. The real superpotential corresponding to any exactly solved linear Schrödinger equation may be used to find a complex-potential for which exact localized nonlinear modes for the NLSE can be obtained. The solutions with singular phases are obtained for a few complex potentials.

Modal analysis and extraction method for the frame structure considering soil-structure interaction effect

For a soil-structure interaction (SSI) system, the direct method can analyze the dynamic characteristics of the arbitrary complicated soil deposits. However, to determine the radiation damping effect on the structural dynamic characteristics, the complex modal analysis using the direct method needs to calculate many complex modes for obtaining the few exact structural modes due to a large number of soil degrees of freedom. The needed structural modes among a large amount of soil modes are difficult to be extracted. In this paper, a new complex modal analysis method using sequential eigenvalue-shift is developed for the calculation of the modal parameters of the frame structure under SSI effect. Accordingly, a new index of the local modal mass ratio is proposed to quickly and accurately extract the structural modes from many combinations of modes from structures and soil. Several comprehensive examples are presented to validate the proposed method, and the influence of artificial boundary on the natural frequency, mode and modal damping ratio of the structure is investigated.

SAMA: Self-adjusting multi-cycle approximate adder

Approximate computing is a promising approach that leads to a better compromise between power and delay by trading an acceptable level of accuracy in inherently error resilient applications. In this paper, we present a runtime accuracy configurable approximate adder that can operate in both approximate and exact modes. It provides a better compromise between power, delay, and accuracy compared with state-of-the-art approximate adders at high accuracies. Our evaluations show that the proposed adder can make up to 45% and 79% improvements in power-delay product (PDP) and energy-delay product (EDP), respectively, compared with state-of-the-art approximate adders, at high accuracies. In the accurate mode, the improvements in the PDP and EDP are up to 58% and 82%, respectively. The use of the proposed adder in an image processing application and in a mean-squares prediction algorithm confirms its superiority over existing circuits in terms of PDP and EDP.

A smart chemosensor with different response mechanisms to multi-analytes: Chromogenic and fluorogenic recognition of Cu2+, Fe3+, and Zn2+

Single-component sensors that can detect multiple analytes have drawn great research attentions. Herein, a smart chemosensor TPBS that can recognize multiple targets was developed by connecting triphenylamine with benzothiazole via an imine link. The N atoms with lone pair electrons on the flexible imine link served as potential coordination sites to allow for variations in charge transfer and molecular configurations. In CH3CN, TPBS simultaneously achieved the recognition of Cu2+ through a chromogenic response (colorless to red) via ligand-metal charge transfer, and the recognition of Fe3+ through a “turn-on” fluorogenic response (non-emission to blue) via the chelation-enhanced fluorescence effect. In aqueous solution, TPBS recognized Zn2+ via a “turn-on” fluorogenic response (non-emission to green) based on the aggregation-induced emission behavior. The detection limits were as low as 0.45 μM, 3.24 μM, and 3.22 μM for Cu2+, Fe3+, and Zn2+, respectively. A 1:1 binding stoichiometry and exact complex modes between TPBS and the target metal ions were deduced using Job's plot and FT-IR analyses. Both experiments and theoretical calculations supported the deduced coordination mechanisms. The ability of TPBS to recognize Cu2+, Fe3+, and Zn2+ was then tested in real-life water samples and through on-site detection of Zn2+ using test strips.

Comparative modal analysis in micro–nano-optical fiber tapers using spectral parameter power series method and exact modes method

This work presents a comparative theoretical analysis of spatial modal evolution in micro/nano-optical fiber (MNF) tapers. The study proposes the use of the Spectral Parameter Power Series (SPPS) Method and compares its performance with results from the so-called Exact Modes Method (EMM) and the Finite Element Method (FEM) (the method employed by the COMSOL© software in which the computations were implemented). By using these techniques, the modal analysis and intensity evolution are discussed along different sections of the optical fiber taper. Furthermore, the data are compared considering experimental values from a real micro/nano-optical fiber taper sample. The SPPS method offers a competitive accuracy and versatility to deal with graded index profiles, its computational costs are low, and its implementation is relatively easy. The results from the SPPS method fit to those of the EM method, which sometimes involves intricated models, and those of the FEM, which may require more computational time. The SPPS method offers an average relative error of less than 5% with respect to the exact method with less computational cost compared to the FEM method for radii bigger than 2 μm at 1550 nm.

Lesion analysis of forensic autopsies of violent traffic deaths at HOGIP over a two-year period

The violence of road accidents leads to frequent and particularly complex deaths requiring the intervention of forensic medicine. The objective of this study is to determine, with the help of autopsies, the socio-demographic profile, the exact causes and modes of death of traffic accident victims. Materials and methods: This is a retrospective study based on data collected from court requisitions, autopsy reports and registers of the General Hospital Idrissa Pouye of Grand Yoff in Dakar from January 1, 2020 to December 31, 2021. Results: The gender distribution of the present study showed a higher proportion of males (74%) compared to females (26%). The distribution of traffic fatalities shows 2 peaks, between the age groups of 15-30 years and 31-45 years. Our study shows that the majority of fatal road traffic accidents occur in rural areas. In our study, we found varied monthly peaks with virtually the same rates in the months of February, May, June, September and October. In the present study, polytraumatic injuries were responsible for 35% of the deaths followed by head injuries at 25%, i.e. a total of 60% of deaths.Lesions with neurological complications (14%), infectious complications (11%), internal bleeding (11%) and external bleeding (4%) were responsible for the deaths. Conclusion: Traffic accidents, with their exponential number of deaths, constitute a real public health problem. The knowledge of the modes of these accidental deaths and fatal injuries, especially in young people, is possible thanks to the contribution of the medicolegal autopsy.

Accuracy Configurable Adders with Negligible Delay Overhead in Exact Operating Mode

In this paper, two accuracy configurable adders capable of operating in approximate and exact modes are proposed. In the adders, which include a block-based carry propagate and a parallel prefix structure, the carry chains are cut off in the approximate mode limiting the carry chain depth to two blocks. In the case of parallel prefix adder, we propose a special carry generate tree equipped with a power gating means. In both of the proposed structures, the critical paths of the adders are not increased in the exact operating mode. Thus, the main objective of proposing these approximate adder structures is to present an accuracy configurable adder structure whose delay in the exact mode is almost the same as an exact adder. The efficacies of the proposed accuracy configurable adders are compared with some state-of-the-art adder structures using a 15nm CMOS technology. In addition, their efficacies are evaluated in two error-resilient applications. These studies show that the proposed carry-propagate adder has 22% (51%) lower energy consumption (error rate) compared to the best prior works. Also, the proposed parallel prefix adder provides, on average, 20% lower energy consumption compared to the exact parallel prefix adders.

Quasinormal modes from bound states: The numerical approach

It is known that the spectrum of quasinormal modes of potential barriers is related to the spectrum of bound states of the corresponding potential wells. This property has been widely used to compute black hole quasinormal modes, but it is limited to a few ``approximate'' potentials with certain transformation properties for which the spectrum of bound states must be known analytically. In this work we circumvent this limitation by proposing an approach that allows one to make use of potentials with similar transformation properties, but where the spectrum of bound states can also be computed numerically. Because the numerical calculation of bound states is usually more stable than the direct computation of the corresponding quasinormal modes, the new approach is also interesting from a technical point of view. We apply the method to different potentials, including the P\"oschl-Teller potential for which all steps can be understood analytically, as well as potentials for which we are not aware of analytic results but provide independent numerical results for comparison. As a canonical test, all potentials are chosen to match the Regge-Wheeler potential of axial perturbations of the Schwarzschild black hole. We find that the new approximate potentials are more suitable to approximate the exact quasi-normal modes than the P\"oschl-Teller potential, particularly for the first overtone. We hope this work opens new perspectives to the computation of quasinormal modes and finds further improvements and generalizations in the future.

Monkeypox and the health-care environment

Historically, fewer than a dozen cases of health care-associated human monkeypox have been reported in endemic African countries, including in the Democratic Republic of Congo (1983),1 Republic of the Congo (2003),2 Central African Republic (2015–16),3 and Nigeria (2017–18).4 Although all of these exposures occurred in hospital environments, the exact modes of transmission could not be identified. Among healthcare-associated monkeypox cases exported to countries outside of Africa between 2003 and 2021, at least 250 health-care workers have had variable unprotected exposures to the monkeypox virus in the hospital setting;5 however, only one case of nosocomial transmission has been reported in the literature.