Symplectic N and time reversal in frustrated magnetism

Identifying the time reversal symmetry of spins as a symplectic symmetry, we develop a large N approximation for quantum magnetism that embraces both antiferromagnetism and ferromagnetism. In SU(N), N>2, not all spins invert under time reversal, so we have introduced a new large N treatment which builds interactions exclusively out of the symplectic subgroup [SP(N)] of time reversing spins, a more stringent condition than the symplectic symmetry of previous SP(N) large N treatments. As a result, we obtain a mean field theory that incorporates the energy cost of frustrated bonds. When applied to the frustrated square lattice, the ferromagnetic bonds restore the frustration dependence of the critical spin in the Neel phase, and recover the correct frustration dependence of the finite temperature Ising transition.Comment: added reference

Dissolved silicon and nitrogen in glacial rivers and water of Blago bay (Russian Arctic, Novaya Zemlya): origin, variability and spreading

Hydrochemical studies of watercourses and the water area of Blagopoluchia bay (Novaya Zemlya, Arctic, Russia) have been carried out. The concentrations of nutrients in rivers and streams are higher than those in the water area of Blagopoluchia bay. It is shown that the concentration of silicon in constantly flowing rivers is 1–13 μM, the concentration of NO3 — 0.5–8, for small and temporary streams these values are higher and are in the range of 18–46 μM Si, 1–11 μM NO3– . The influence of streams and rivers flowing into Blagopoluchia Bay on the water area of the bay is local and extends to 1 km from the mouth, and does not influence the Kara Sea nutrient content.Hydrochemical studies of watercourses and the water area of Blagopoluchia bay (Novaya Zemlya, Arctic, Russia) have been carried out. The concentrations of nutrients in rivers and streams are higher than those in the water area of Blagopoluchia bay. It is shown that the concentration of silicon in constantly flowing rivers is 1–13 μM, the concentration of NO3 — 0.5–8, for small and temporary streams these values are higher and are in the range of 18–46 μM Si, 1–11 μM NO3– . The influence of streams and rivers flowing into Blagopoluchia Bay on the water area of the bay is local and extends to 1 km from the mouth, and does not influence the Kara Sea nutrient content

Slow gait speed and cardiac rehabilitation participation in older adults after acute myocardial infarction

Background Lack of participation in cardiac rehabilitation ( CR ) and slow gait speed have both been associated with poor long‐term outcomes in older adults after acute myocardial infarction ( AMI ). Whether the effect of CR participation on outcomes after AMI differs by gait speed is unknown. Methods and Results We examined the association between gait speed and CR participation at 1 month after discharge after AMI , and death and disability at 1 year, in 329 patients aged ≥65 years enrolled in the TRIUMPH (Translational Research Investigating Underlying Disparities in Recovery From Acute Myocardial Infarction: Patients' Health Status) registry. Among these patients, 177 (53.7%) had slow gait speed (&lt;0.8 m/s) and 109 (33.1%) participated in CR . Patients with slow gait speed were less likely to participate in CR compared with patients with normal gait speed (27.1% versus 40.1%; P =0.012). In unadjusted analysis, CR participants with normal gait speed had the lowest rate of death or disability at 1 year (9.3%), compared with those with slow gait speed and no CR participation (43.2%). After adjustment for cardiovascular risk factors and cognitive impairment, both slow gait speed (odds ratio, 2.30; 95% confidence interval, 1.30–4.06) and non‐ CR participation (odds ratio, 2.34; 95 confidence interval, 1.22–4.48) were independently associated with death or disability at 1 year. The effect of CR on the primary outcome did not differ by gait speed ( P =0.70). Conclusions CR participation is associated with reduced risk for death or disability after AMI . The beneficial effect of CR participation does not differ by gait speed, suggesting that slow gait speed alone should not preclude referral to CR for older adults after AMI . </jats:sec

Kinetics of viral self-assembly: the role of ss RNA antenna

A big class of viruses self-assemble from a large number of identical capsid proteins with long flexible N-terminal tails and ss RNA. We study the role of the strong Coulomb interaction of positive N-terminal tails with ss RNA in the kinetics of the in vitro virus self-assembly. Capsid proteins stick to unassembled chain of ss RNA (which we call "antenna") and slide on it towards the assembly site. We show that at excess of capsid proteins such one-dimensional diffusion accelerates self-assembly more than ten times. On the other hand at excess of ss RNA, antenna slows self-assembly down. Several experiments are proposed to verify the role of ss RNA antenna.Comment: 4 pages, 3 figures, several experiments are proposed, a new idea of experiment is adde

Remarkably robust and correlated coherence and antiferromagnetism in (Ce1−x_{1-x}Lax_x)Cu2_2Ge2_2

We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce$_{1-x}$La$_x$)Cu$_2$Ge$_2$ single crystals (0 $\leq x\leq$ 1). With La substitution, the antiferromagnetic temperature $T_N$ is suppressed in an almost linear fashion and moves below 0.36 K, the base temperature of our measurements for $x>$ 0.8. Surprisingly, in addition to robust antiferromagnetism, the system also shows low temperature coherent scattering below $T_{coh}$ up to $\sim$ 0.9 of La, indicating a small percolation limit $\sim$ 9$\%$ of Ce that separates a coherent regime from a single-ion Kondo impurity regime. $T_{coh}$ as a function of magnetic field was found to have different behavior for $x$ 0.9. Remarkably, $(T_{coh})^2$ at $H$ = 0 was found to be linearly proportional to $T_N$. The jump in the magnetic specific heat $\delta C_{m}$ at $T_N$ as a function of $T_K/T_N$ for (Ce$_{1-x}$La$_x$)Cu$_2$Ge$_2$ follows the theoretical prediction based on the molecular field calculation for the $S$ = 1/2 resonant level model

Ultrasonic noise emissions from wind turbines: potential effects on bat species

The impact that wind turbines have on the environment, particularly with respect to wildlife such as bat species, has generated increasing concern over the last decade. Although the harnessing of wind power is becoming much more widespread as a clean, renewable energy resource, the increasing global turbine mortality rates for bats are thought to be significantly detrimental to susceptible species. Much research is still needed to fully understand the ways in which turbines affect bats, since they rely on echolocation and audible cues to hunt and navigate, therefore having a unique acoustic perspective of objects in their vicinity. Here we present an overview of what is currently known regarding ultrasonic emissions from operational wind turbine structures, including noise generated from the gearing mechanism, rotor, or through blade defects, and how such noise may be perceptible to some bat species in the local turbine habitat

Density waves theory of the capsid structure of small icosahedral viruses

We apply Landau theory of crystallization to explain and to classify the capsid structures of small viruses with spherical topology and icosahedral symmetry. We develop an explicit method which predicts the positions of centers of mass for the proteins constituting viral capsid shell. Corresponding density distribution function which generates the positions has universal form without any fitting parameter. The theory describes in a uniform way both the structures satisfying the well-known Caspar and Klug geometrical model for capsid construction and those violating it. The quasiequivalence of protein environments in viral capsid and peculiarities of the assembly thermodynamics are also discussed.Comment: 8 pages, 3 figur