Tunable dual plasmon-induced transparency and slow-light analysis based on monolayer patterned graphene metamaterial

We propose a novel terahertz metamaterial structure based on patterned monolayer graphene. This structure produces an evident dual plasmon-induced transparency (PIT) phenomenon due to destructive interference between bright and dark modes. Since the Fermi level of graphene can be adjusted by an external bias voltage, the PIT phenomenon can be tuned by adjusting the voltage. Then the coupled-mode theory (CMT) is introduced to explore the internal mechanism of the PIT. After that, we investigate the variation of absorption rate at different graphene carrier mobilities, and it shows that the absorption rate of this structure can reach 50%, which is a guideline for the realization of graphene terahertz absorption devices. In addition, through the study of the slow-light performance for this structure, it is found that its group index is as high as 928, which provides a specific theoretical basis for the study of graphene slow-light devices.

Optical tunable multifunctional slow light device based on double monolayer graphene grating-like metamaterial

A very simple optical tunable device, which can realize multiple functions of frequency selection, reflection and slow light, is presented at the investigation. The proposed device is constructed by a periodic grating-like structure. There are two dielectrics (graphene and silicon) in a period of the equivalent grating. The incident light will strongly resonate with the graphene of electrostatic doping, forming an evanescent wave propagating along the surface of graphene, and this phenomenon is the surface plasmon. Under constructive interference of the polaritons, a unique plasmonic induced transparency phenomenon will be achieved. The induced transparency produced by this device can be well theoretically fitted by the bright and dark mode of optical equivalent cavity which can be called coupled mode theory (CMT). This theory can well analyze the influence of various modes and various losses between the function of this device. The device can use gate voltages for electrostatic doping in order to change the graphene carrier concentration and tune the optical performance of the device. Moreover, the length of the device in y-direction is will be much larger than the length of single cycle, providing some basis for realizing the fast tunable function and laying a foundation for the integration. Through a simulation and calculation, we can find that the group index and group delay of this device are as high as 515 and 0.257 picoseconds (ps) respectively, so it can provide a good construction idea for the slow light device. The proposed grating-like metamaterial structure can provide certain simulation and theoretical help for the optical tunable reflectors, absorbers, and slow light devices.

The Role of Electrochemistry and Mineralogy in the Geotechnical Behavior of Salinized Soils

The Atterberg limits are essential information and the first step in soil classification for geotechnical purposes. Established laboratoryprocedures use distilled water in the plasticity and liquid limits determination. However, saline solutions frequently interact with soilsin the construction environment through fluid percolation processes. This work aims to understand the variation of the geotechnicalbehavior of two standard materials with different mineralogical compositions (kaolinitic and smectitic) when affected by NaCl ionicsolutions in different concentrations. The purpose is to simulate different soils in environments with the presence of saline solutions.This paper reports an experimental program in which a kaolinite-rich and a smectite-rich material received NaCl solutions in threedifferent concentrations (0.6 %, 3.5 %, and 15.0 %) and had their Atterberg limits determined under these conditions. Additionally,non-contaminated samples of both materials have had their limits measured using distilled water. Physical characterization testsincluded hygroscopic moisture, grain size distribution, grain density, plastic limit (PL), and liquid limit (LL). These data allowed thedetermination of the Skempton activity index (AI), plasticity index (PI), consistency index (CI), classification of soils in the UnifiedSoil Classification System (USCS), and in the Highway Research Board (HRB) with the group index (GI). Mineralogy was determinedby X-ray diffraction and physical chemistry by measuring pH in H2O and KCl, determining the ΔpH, the point of zero-charge (PZC),and the surface electrical potential (Ψo). The results show that the pH values rise with increasing salinity, while ΔpH, PZC, Ψo, LL,AI, PI, GI decrease with increasing salinity. The PL decreases with the increase in salinity for smectite and increases for kaolinite. TheUSCS and HRB demonstrate that the materials start to behave as fewer plastic materials with increased salinity. It is concluded that thevariations in the physicochemical parameters of the environment control and modify the geotechnical behavior of the fine-grained soils.

Slow Light Tuning in Annular Slotted Photonic Crystal Waveguide with Incoming Polymer

An advanced post-processing scheme of reconfigurable dielectric infiltration into an annular slotted photonic crystal waveguide (ASPhCW) is proposed in this paper. Ionic liquids have had prominent effects in enhancing the optical properties of photonic crystals, especially in the aspect of tuning the transmission rate and velocity through optical materials. Using the two-dimensional plane wave expansion method, the flat band dispersion of the slow light is obtained and the tuning of the operating wavelength of the crystal could be realized by incoming polymer technology. The operating wavelength tuning range could be as large as 459.27nm and the group index could be tuned as high as 44.8 with a near zero group velocity dispersion. Using this method, a high group index equaling 45 with the bandwidth equaling 11.3nm and the normalized delay bandwidth product (NDBP) equaling 0.25 is realized. This incoming polymer technology provides an effective method of getting flat band of slow light flexibly and makes it possible to offer longer delay and low group velocity after fabrication.

Scattering amplitudes for all masses and spins

We introduce a formalism for describing four-dimensional scattering amplitudes for particles of any mass and spin. This naturally extends the familiar spinor-helicity formalism for massless particles to one where these variables carry an extra SU(2) little group index for massive particles, with the amplitudes for spin S particles transforming as symmetric rank 2S tensors. We systematically characterise all possible three particle amplitudes compatible with Poincare symmetry. Unitarity, in the form of consistent factorization, imposes algebraic conditions that can be used to construct all possible four-particle tree amplitudes. This also gives us a convenient basis in which to expand all possible four-particle amplitudes in terms of what can be called “spinning polynomials”. Many general results of quantum field theory follow the analysis of four-particle scattering, ranging from the set of all possible consistent theories for massless particles, to spin-statistics, and the Weinberg-Witten theorem. We also find a transparent understanding for why massive particles of sufficiently high spin cannot be “elementary”. The Higgs and Super-Higgs mechanisms are naturally discovered as an infrared unification of many disparate helicity amplitudes into a smaller number of massive amplitudes, with a simple understanding for why this can’t be extended to Higgsing for gravitons. We illustrate a number of applications of the formalism at one-loop, giving few-line computations of the electron (g − 2) as well as the beta function and rational terms in QCD. “Off-shell” observables like correlation functions and form-factors can be thought of as scattering amplitudes with external “probe” particles of general mass and spin, so all these objects — amplitudes, form factors and correlators, can be studied from a common on-shell perspective.

SELECTION OF THE RATIO OF MICROBIAL COMPONENTS TO ACCELERATE THE BIODEGRADATION OF BIRD DROPPINGS

The aim of presented studies was to select the optimal ratio of the proteolytic culture of Pseudomonas putida 90 biovar A (171) and a strain that has the properties of fixing atmospheric nitrogen ‒ Azotobacter chroococcum 31/8 R to accelerate the process of biodegradation of chicken droppings to indicators of the relevant regulatory documentation. In conducted studies, the following indicators were analyzed: content of ammonium nitrogen, total microbial number, ammonia nitrogen, index of bacteria of the escherichia coli group, index of enterococci and pathogenic microorganisms, eggs and larvae of helminths, and the hazard class of processed and untreated chicken droppings was determined by the calculation method. As a result of conducted physico-chemical and sanitary-biological analyses, it was found that a more optimal and stable result was revealed when processing chicken droppings with the studied cultures in a ratio of 1:1. This treatment of droppings with cultures contributed to a 15-day decrease in the level of ammonium nitrogen in the by-product from 278 mg/l to 97 mg/l, the content of ammonia in the environment from 84 mg/m3 to 13 mg/m3, index of bacteria of the escherichia coli group from 4 to 1 units, index of enterococci from 5 to 2 units, index of pathogenic microorganisms from 2 to 0 units, number of eggs and larvae of helminths from 8 to 0 copies, number of larvae of synanthropic flies from 2 to 0 copies at the same time increasing the total microbial number to a value of at least 1011 cells/g. The hazard class of chicken droppings treated with microbial research objects decreased from III to IV and met the requirements of GOST 31461-2012.

An optical parametric Bragg amplifier on a CMOS chip

We demonstrate a complementary metal–oxide–semiconductor (CMOS)-compatible optical parametric Bragg amplifier on an ultra-silicon-rich nitride chip. The amplifier design incorporates advantageous group index properties in a nonlinear Bragg grating to circumvent phase matching limitations arising from the bulk material and waveguide dispersion. The grating structure further augments the effective nonlinear parameter of 800 W−1/m, considerably lowering the power required for the observation of strong parametric gain. On/off optical parametric gain of 20 dB is achieved using a low peak power of 1.6 W, in good agreement with numerical calculations. This represents a 7 dB improvement in the parametric gain compared to the absence of grating enhancement which is attributed to the Bragg grating induced superior phase matching.

Submicrometer perovskite plasmonic lasers at room temperature

Plasmonic lasers attracted interest for their ability to generate coherent light in mode volume smaller than the diffraction limit of photonic lasers. While nanoscale devices in one or two dimensions were demonstrated, it has been difficult to achieve plasmonic lasing with submicrometer cavities in all three dimensions. Here, we demonstrate submicrometer-sized, plasmonic lasers using cesium-lead-bromide perovskite (CsPbBr3) crystals, as small as 0.58 μm by 0.56 μm by 0.32 μm (cuboid) and 0.79 μm by 0.66 μm by 0.18 μm (plate), on polymer-coated gold substrates at room temperature. Our experimental and simulation data obtained from more than 100 plasmonic and photonic devices showed that enhanced optical gain by the Purcell effect, large spontaneous emission factor, and high group index are key elements to efficient plasmonic lasing. The results shed light on the three-dimensional miniaturization of plasmonic lasers.

Both partners practicing orgasmic meditation report having a mystical-type experience: results using the Mystical Experience Questionnaire

Background: Practitioners in a variety of spiritual/religious traditions have described “mystical experiences”, defined by a common set of qualities. The “Mystical Experience Questionnaire” (MEQ30) provides a validated and quantitative measure of mystical experience, and has been used successfully to demonstrate that the hallucinogenic substance psilocybin triggers a mystical-type experience. Orgasmic Meditation (OM) is a structured, partnered meditative practice involving manual stimulation of the clitoris. Although the partners in an OM have different roles (one is stroking, and the other is being stroked), both claim benefit from the practice. The aim of the current study is to use the MEQ30 to assess to what extent participants report mystical experiences during OM, and to what extent that experience is correlated between the partners. Methods: In Study 1, 780 participants completed the MEQ30 with a single powerful OM in mind. In Study 2, 56 pairs of participants (both partners) completed the MEQ30 after their next OM. If the respondent had a score ≥60% of the maximum possible score on each of the four subscales of the MEQ30, this was considered a “complete” mystical experience. Results: Respondents from Study 1 reported an MEQ total score of 3.35 (SD = 1.08), with 62% of respondents reporting a complete mystical experience. Respondents from Study 2 reported an MEQ total score of 3.21 (SD = 0.92), with 23% reporting a complete mystical experience. We found strong relationships between MEQ total score and role (i.e., stroker or strokee), interrater agreement within-group index (aWG) = 0.46, and an even stronger relationship between partners and MEQ total score, aWG=0.71. Conclusions: These findings suggest that OM can trigger a substantial mystical experience in both partners. Whether the brains of people who OM show similar activity changes to those having other mystical experiences awaits future study.