Background: This is the first study to compare plasma and cerebrospinal fluid (CSF) pharmacokinetics of intravenous (IV), oral (PO), or rectal (PR) formulations of acetaminophen. Methods: Healthy male subjects (N = 6) were randomized to receive a single dose of IV (OFIRMEV Ò ; Cadence) 1,000 mg (15 minute infusion), PO (2 Tylenol Ò 500 mg caplets; McNeil Consumer Healthcare), or PR acetaminophen (2 Feverall Ò 650 mg suppositories; Actavis) with a 1-day washout period between doses. The 1,300 mg PR concentrations were standardized to 1,000 mg. Acetaminophen plasma and CSF levels were obtained at T0, 0.25, 0.5, 0.75, 1, 2, 3, 4, and 6 hours.Results: IV acetaminophen showed earlier and higher plasma and CSF levels compared with PO or PR administration. CSF bioavailability over 6 hours (AUC 0-6 ) for IV, PO, and PR 1 g was 24.9, 14.2, and 10.3 lgAEh/mL, respectively. No treatment-related adverse events were reported. One subject was replaced because of premature failure of his lumbar spinal catheter. The mean CSF level in the IV group was similar to plasma from 3 to 4 hours and higher from 4 hours on. Absorption phase, variability in plasma, and CSF were greater in PO and PR groups than variability with IV administration.Conclusions: These results demonstrate that earlier and greater CSF penetration occurs as a result of the earlier and higher plasma peak with IV administration compared with PO or PR. n

The Eynard-Orantin topological recursion relies on the geometry of a Riemann surface S and two meromorphic functions x and y on S. To formulate the recursion, one must assume that x has only simple ramification points. In this paper we propose a generalized topological recursion that is valid for x with arbitrary ramification. We justify our proposal by studying degenerations of Riemann surfaces. We check in various examples that our generalized recursion is compatible with invariance of the free energies under the transformation (x, y) → (y, x), where either x or y (or both) have higher order ramification, and that it satisfies some of the most important properties of the original recursion. Along the way, we show that invariance under (x, y) → (y, x) is in fact more subtle than expected; we show that there exists a number of counter examples, already in the case of the original Eynard-Orantin recursion, that deserve further study.1. the ramification points of x and y must not coincide; 2. the ramification points of x must all be simple. The Eynard-Orantin topological recursionIn this section we review the original topological recursion formulated by Eynard and Orantin in [16,18]. We will use the notation put forward by Prats Ferrer in [27].

We study potential scattering in a two-dimensional electron gas with Rashba spin-orbit coupling in the limit that the energy of the scattering electron approaches the bottom of the lower spin-split band. Focusing on two spin-independent circularly symmetric potentials, an infinite barrier and a delta-function shell, we show that scattering in this limit is qualitatively different from both scattering in the higher spin-split band and scattering of electrons without spin-orbit coupling. The scattering matrix is purely off-diagonal with both off-diagonal elements equal to one, and all angular momentum channels contribute equally; the differential cross section becomes increasingly peaked in the forward and backward scattering directions; the total cross section exhibits quantized plateaus. These features are independent of the details of the scattering potentials, and we conjecture them to be universal. Our results suggest that Rashba scattering in the low-energy limit becomes effectively one-dimensional.Comment: corrected typo in Eq. (27). 10 pages, 6 figure

Rashba spin-orbit coupling appears in 2D systems lacking inversion symmetry, and causes the spinsplitting of otherwise degenerate energy bands into an upper and lower helicity band. In this paper, we explore how impurity scattering affects transport in the ultra-low density regime where electrons are confined to the lower helicity band. A previous study has investigated the conductivity in this regime using a treatment in the first Born approximation. In this work, we use the full T -matrix to uncover new features of the conductivity. We first compute the conductivity within a semiclassical Boltzmann framework and show that it exhibits an unconventional density dependence due to the unusual features of the group velocity in the single particle dispersion, as well as quantized plateaus as a function of the logarithm of the electron density. We support this with a calculation using the Kubo formula and find that these plateaus persist in the full quantum theory. We suggest that this quantization may be seen in a pump-probe experiment.

The two electron configuration in the Helium atom is known to very high precision. Yet, we tend to refer to this configuration as a 1s ↑ 1s ↓ singlet, where the designations refer to Hydrogen orbitals. The high precision calculations utilize basis sets that are suited for high accuracy and ease of calculation, but do not really aid in our understanding of the electron configuration in terms of product states of Hydrogen orbitals. Since undergraduate students are generally taught to think of Helium, and indeed, the rest of the periodic table, in terms of Hydrogenic orbitals, we present in this paper a detailed spectral decomposition of the two electron ground state for Helium in terms of these basis states. The 1s ↑ 1s ↓ singlet contributes less than 93% to the ground state configuration, with other contributions coming from both bound and continuum Hydrogenic states.