Heavy Tetraquarks in the Diquark-Antidiquark Picture

The homogeneous Lippmann-Schwinger integral equation is solved in momentum space to calculate the masses of heavy tetraquarks with hidden charm and bottom. The tetraquark bound states are studied in the diquark-antidiquark picture as a two-body problem. A regularized form of the diquark-antidiquark potential is used to overcome the singularity of the confining potential at large distances or small momenta. Our numerical results indicate that the relativistic effect leads to a small reduction in the mass of heavy tetraquarks, which is less than $2\,\%$ for charm and less than $0.2\,\%$ for bottom tetraquarks. The calculated masses of heavy tetraquarks for $1s$, $1p$, $2s$, $1d$ and $2p$ states are in good agreement with other theoretical calculations and experimental data. Our numerical analysis predict the masses of heavy tetraquarks for $3s$, $2d$ and $3p$ states for the first time, and we are not aware of any other theoretical results or experimental data for these states

Correlation between biofilm formation and antibiotic resistance in pseudomonas aeruginosa: A meta-analysis

Biofilm formation is one of the important resistance mechanisms in Pseudomonas aeruginosa. This study aimed to consider the correlation between biofilm formation and antibiotic resistance in Pseudomonas aeruginosa through a systematic review and meta-analysis. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) strategies. Scientific databases were searched by MeSH terms and keywords such as �Pseudomonas aeruginosa�, �biofilm formation�, �antibiotic resistance�, �prevalence� AND �Iran�, to obtain articles published from 1st January 2016 to 30th November 2019. Studies recording biofilm formation and antibiotic resistance in P. aeruginosa recovered from clinical samples of Iranian patients were included. Data analysis was performed using CMA software. The combined biofilm formation rate was reported as 87.6 (95 CI: 80-92.5). The heterogeneity index among the selected articles was Q2=96.5, I2=85.5, and t=0.26 (p=0.16). The pooled occurrences of strong, moderate and weak biofilms were 47.7 (95 CI: 28.7-67.3), 30.2 (95 CI: 19.4-43.8), and 27.4 (95 CI: 8.8-59.8), respectively. The pooled prevalence of MDR P. aeruginosa strains was as follows: 62.5 (95 CI: 40-77.2). The highest combined rates of antibiotic resistance were against ceftriaxone and tobramycin with the rates of 79.2.9 (95 CI: 54.2-96.2) and 64.4 (95 CI: 36.3-92), respectively. Also, the lowermost antibiotic resistance rates were against colistin and polymyxin B, with the prevalence of 2.1 (95 CI: 0.2-18.1), and 3 (95 CI: 0.5-17.3), respectively. More than half of the studies included in the present review showed a significant correlation between biofilm formation and antibiotic resistance pattern. © 2020, EDIMES Edizioni Medico Scientifiche. All rights reserved

Linear and nonlinear tunable optical properties of intersubband transitions in GaN/AlN quantum dots in presence and absence of wetting layer

In this study we have performed a numerical approach to investigate the optical properties of GaN/AlN quantum dots (QDs). We have used nice homemade finite element method (FEM) codes to solve the Schrödinger equation, in presence and absence of wetting layer. The optical properties of both well-known, truncated pyramids–shaped, wurtize (WZ) and zinc blande (ZB) QDs have been investigated. It is demonstrated, there is slight amount of difference between all orders of absorption coefficients and relative refractive index changes (RRIC) for both structures. The effect of relaxation rate studied as well. Overlay it is shown that the optical properties ZB/WZ QDs could be engineered in well-manner

Tunneling Control of Transmission Coefficient and Group Index in a Quantum Dot Nanostructure

We theoretically study the transmission and group index properties of the probe field in a four-level quantum dot molecule. It is found that the tunnel coupling plays a very important role in realizing the transmission coefficient of the probe field. Moreover, the impact of an incoherent pump field on imaginary part of susceptibility is investigated. We show that probe transmission exhibits oppositional behavior against weak and strong incoherent pump rates. This approach allows substantial flexibility in the manipulation of group velocity of light

Tunneling Control of Transmission Coefficient and Group Index in a Quantum Dot Nanostructure

We theoretically study the transmission and group index properties of the probe field in a four-level quantum dot molecule. It is found that the tunnel coupling plays a very important role in realizing the transmission coefficient of the probe field. Moreover, the impact of an incoherent pump field on imaginary part of susceptibility is investigated. We show that probe transmission exhibits oppositional behavior against weak and strong incoherent pump rates. This approach allows substantial flexibility in the manipulation of group velocity of light

Dynamics of phase oscillator networks with synaptic weight and structural plasticity

We study the dynamics of Kuramoto oscillator networks with two distinct adaptation processes, one varying the coupling strengths and the other altering the network structure. Such systems model certain networks of oscillatory neurons where the neuronal dynamics, synaptic weights, and network structure interact with and shape each other. We model synaptic weight adaptation with spike-timing-dependent plasticity (STDP) that runs on a longer time scale than neuronal spiking. Structural changes that include addition and elimination of contacts occur at yet a longer time scale than the weight adaptations. First, we study the steady-state dynamics of Kuramoto networks that are bistable and can settle in synchronized or desynchronized states. To compare the impact of adding structural plasticity, we contrast the network with only STDP to one with a combination of STDP and structural plasticity. We show that the inclusion of structural plasticity optimizes the synchronized state of a network by allowing for synchronization with fewer links than a network with STDP alone. With non-identical units in the network, the addition of structural plasticity leads to the emergence of correlations between the oscillators’ natural frequencies and node degrees. In the desynchronized regime, the structural plasticity decreases the number of contacts, leading to a sparse network. In this way, adding structural plasticity strengthens both synchronized and desynchronized states of a network. Second, we use desynchronizing coordinated reset stimulation and synchronizing periodic stimulation to induce desynchronized and synchronized states, respectively. Our findings indicate that a network with a combination of STDP and structural plasticity may require stronger and longer stimulation to switch between the states than a network with STDP only

Potato extract as reducing agent and stabiliser in a facile green one-step synthesis of ZnO nanoparticles

<div><p>A facile green recipe was developed to synthesise highly pure, safe and durable zinc oxide nanoparticles (ZnO Nps) using homemade starch-rich potato extract. The ZnO Nps were synthesised using zinc nitrate and potato extract, and the whole reaction is carried out for 30 min at 80 °C. In the synthesis, starch-rich potato extract acted as the reducing agent and as a stabilising layer on freshly formed ZnO Nps. Hexagonal (wurtzite) shaped ZnO Nps with size about 20 ± 1.2 nm were synthesised and characterised using X-ray diffraction, transition electron microscope and scanning microscopy analyses. Fourier transform infrared spectral analysis indicated that highly pure ZnO nanopowders were obtained at higher temperatures. The use of environmentally benign and renewable material as the respective reducing and protecting agents, starch-rich potato extract, as well as a gentle solvent medium (H₂O), offered a simple and quite efficient procedure for the synthesis of ZnO Nps in neutral medium with promising potential for biological and biomedical applications.</p></div