Universal TT-linear resistivity and Planckian dissipation in overdoped cuprates

International audienceThe perfectly linear temperature dependence of the electrical resistivity observed as T$\rightarrow$ 0 in a variety of metals close to a quantum critical point is a major puzzle of condensed-matter physics . Here we show that T-linear resistivity as T$\rightarrow$0 is a generic property of cuprates, associated with a universal scattering rate. We measured the low-temperature resistivity of the bilayer cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8+\lambda}$ and found that it exhibits a T-linear dependence with the same slope as in the single-layer cuprates Bi$_2$Sr$_2$CuO$_{6+\delta}$ , La$_{1.6−x}$Nd$_{0.4}$Sr$_x$CuO$_4$ and La$_{2−x}$Sr$_x$CuO$_4$ , despite their very different Fermi surfaces and structural, superconducting and magnetic properties. We then show that the T-linear coefficient (per CuO$_2$ plane), A1$^□$, is given by the universal relation A1$^□$T$_F$=$h/2e^2$ , where $e$ is the electron charge, $h$ is the Planck constant and $T_F$ is the Fermi temperature. This relation, obtained by assuming that the scattering rate 1/$\tau$ of charge carriers reaches the Planckian limit, whereby $\hbar$/$\tau$=$k_BT$, works not only for holedoped cuprates but also for electron-doped cuprates, despite the different nature of their quantum critical point and strength of their electron correlations

LLLT for the management of patients with ankylosing spondylitis

This study aimed to compare the effectiveness of the combined low-level laser therapy (LLLT) and passive stretching with combined placebo LLLT laser and the same passive stretching exercises in patients suffering from Αnkylosing spondylitis. Forty-eight patients suffering from Αnkylosing spondylitis participated in the study and were randomized into two groups. Group A (n = 24) was treated with a λ = 820 Ga-Al-As laser CW, with power intensity = 60 mW/cm2, energy per point in each session = 4.5 J, total energy per session = 27.0 J, in contact with specific points technique, plus passive stretching exercises. Group B (n = 24), received placebo laser plus the same passive stretching exercises. Both groups received 12 sessions of laser or placebo within 8 weeks; two sessions per week (weeks 1–4) and one session per week (weeks 5–8). Pain and function scales were completed before the treatment, at the end of the fourth and eighth week of treatment, and 8 weeks after the end of treatment (follow-up). Group A revealed a significant improvement after 8 weeks of treatment in all pain and function scales. At 8-week follow-up, the improvement remained only for the pain, while for all other function outcomes the differences were not statistically significant. The results suggested that after an 8-week treatment and after a follow-up, the combination of LLLT and passive stretching exercises decreased pain more effectively than placebo LLLT along with the same passive stretching exercises in patients with Αnkylosing spondylitis. Future studies are needed to establish the relative and absolute effectiveness of the above protocol

Quinolines and Quinolones as Antibacterial, Antifungal, Antivirulence, Antiviral and Anti-parasitic Agents

Infective diseases have become health threat of a global proportion due to appearance and spread of microorganisms resistant to majority of therapeutics currently used for their treatment. Therefore, there is a constant need for development of new antimicrobial agents, as well as novel therapeutic strategies. Quinolines and quinolones, isolated from plants, animals, and microorganisms, have demonstrated numerous biological activities such as antimicrobial, insecticidal, antiinflammatory, antiplatelet, and antitumor. For more than two centuries quinoline/quinolone moiety has been used as a scaffold for drug development and even today it represents an inexhaustible inspiration for design and development of novel semi-synthetic or synthetic agents exhibiting broad spectrum of bioactivities. The structural diversity of synthetized compounds provides high and selective activity attained through different mechanisms of action, as well as low toxicity on human cells. This review describes quinoline and quinolone derivatives with antibacterial, antifungal, anti-virulent, antiviral, and anti-parasitic activities with the focus on the last 10 years literature