Active Pharmaceutical Ingredients and Aquatic Organisms

The presence of active pharmaceuticals ingredients (APIs) in aquatic systems has led in recent years to a burgeoning literature examining environmental occurrence, fate, effects, risk assessment, and treatability of these compounds. The vast preponderance of studies aimed at identifying and quantifying contaminant residues in aquatic tissues have involved the conventional and legacy pollutants. Comparatively few studies have been targeted at APIs, primarily those that are lipophilic. Although APIs have received much attention as emerging contaminants of concern, it is important to recognize that traditional approaches to understand and predict exposure and effects of other environmental organic contaminant classes mayor may not be appropriate for APIs. For example, traditional approaches for understanding aquatic effects may not be as useful for some APIs (Brooks et al. 2003), but lessons learned from the study of compounds active at the hypothalamicpituitary- gonadal axis (endocrine disruptors/modulators) may reduce uncertainties associated with environmental assessments of other APIs (Ankley et al. 2007)

A correspondence of modular forms and applications to values of L-series

An interpretation of the Rogers–Zudilin approach to the Boyd conjectures is established. This is based on a correspondence of modular forms which is of independent interest. We use the reinterpretation for two applications to values of L-series and values of their derivatives

Energy transfer, pressure tensor and heating of kinetic plasma

Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade and convert kinetic energy into heat are hotly debated. Here we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, $-\left( \boldsymbol{P} \cdot \nabla \right) \cdot \boldsymbol{u}$, can trigger a channel of the energy conversion between fluid flow and random motions, which is a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.Comment: 28 pages, 10 figure

Spacecraft Observations And Analytic Theory Of Crescent-Shaped Electron Distributions In Asymmetric Magnetic Reconnection

Supported by a kinetic simulation, we derive an exclusion energy parameter $\cal{E}_X$ providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell Demon, only high energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low density separatrix. Egedal, J; Le, A; Daughton, W; Wetherton, B; Cassak, P A; Chen, L -J; Lavraud, B; Trobert, R B; Dorelli, J; Gershman, D J; Avanov, L

The Force Balance of Electrons During Kinetic Anti-parallel Magnetic Reconnection

Fully kinetic simulations are applied to the study of 2D anti-parallel reconnection, elucidating the dynamics by which the electron fluid maintains force balance within both the electron diffusion region (EDR) and the ion diffusion region (IDR). Inside the IDR, magnetic field-aligned electron pressure anisotropy ($p_{e\parallel}\gg p_{e\perp})$ develops upstream of the EDR. Compared to previous investigations, the use of modern computer facilities allows for simulations at the natural proton to electron mass ratio $m_i/m_e=1836$. In this high-$m_i/m_e$-limit the electron dynamics changes qualitatively, as the electron inflow to the EDR is enhanced and mainly driven by the anisotropic pressure. Using a coordinate system with the $x$-direction aligned with the reconnecting magnetic field and the $y$-direction aligned with the central current layer, it is well-known that for the much studied 2D laminar anti-parallel and symmetric scenario the reconnection electric field at the $X$-line must be balanced by the $\partial p_{exy}/ \partial x$ and $\partial p_{eyz}/ \partial z$ off-diagonal electron pressure stress components. We find that the electron anisotropy upstream of the EDR imposes large values of $\partial p_{exy}/ \partial x$ within the EDR, and along the direction of the reconnection $X$-line this stress cancels with the stress of a previously determined theoretical form for $\partial p_{eyz}/ \partial z$. The electron frozen-in law is instead broken by pressure tensor gradients related to the direct heating of the electrons by the reconnection electric field. The reconnection rate is free to adjust to the value imposed externally by the plasma dynamics at larger scales.Comment: Submitted to Physics of Plasmas, 11 October 202