Synthesis of Physiologically Active Steroid Esters and Spirolactones

Some steroid hemimalonates, alkylhemimalonates and acetoacetates have been easily prepared in high yields by the reaction of hydroxysteroids with Meldrum acid, its alkyl- and acylderivatives, respectively. Decarboxylation of the hemimalonates and alkylhemimalonates allowed the synthesis of several hydroxysteroid esters, some of them being widely used in medical practice. 17a-hydroxyprogesterone hemimalonate and its acetoacetate, in the presence of bases, undergo cyc1odehydration giving rise to spirolactones which are potential aldosterone antagonists

GABA Withdrawal Modifies Network Activity in Cultured Hippocampal Neurons

Dissociated hippocampal neurons, grown in culture for 2 to 3 weeks, tended to fire bursts of synaptic currents at fairly regular intervals, representing network activity. A brief exposure of cultured neurons to GABA caused a total suppression of the spontaneous network activity. Following a washout of GABA, the activity was no longer clustered in bursts and instead, the cells fired at a high rate tonic manner. The effect of removing GABA could be seen as long as 1 to 2 days after GABA withdrawal and is expressed as an increase in the number of active cells in a network, as well as in their firing rates. Such striking effects of GABA removal may underlie part of the GABA withdrawal syndrome seen elsewhere

Birkhoff strata of the Grassmannian Gr(2)\mathrm{^{(2)}}: Algebraic curves

Algebraic varieties and curves arising in Birkhoff strata of the Sato Grassmannian Gr${^{(2)}}$ are studied. It is shown that the big cell $\Sigma_0$ contains the tower of families of the normal rational curves of all odd orders. Strata $\Sigma_{2n}$, $n=1,2,3,...$ contain hyperelliptic curves of genus $n$ and their coordinate rings. Strata $\Sigma_{2n+1}$, $n=0,1,2,3,...$ contain $(2m+1,2m+3)-$plane curves for $n=2m,2m-1$ $(m \geq 2)$ and $(3,4)$ and $(3,5)$ curves in $\Sigma_3$, $\Sigma_5$ respectively. Curves in the strata $\Sigma_{2n+1}$ have zero genus.Comment: 14 pages, no figures, improved some definitions, typos correcte

g/u(1)dg/u(1)^d parafermions from constrained WZNW theories

The conformal field theory based on the $g/u(1)^d$ coset construction is treated as the WZNW theory for the affine Lie algebra $\hat g$ with the constrained $\hat u(1)^d$ subalgebra.Using a modification of the generalized canonical quantization method generators and primary fields of an extended symmetry algebra are found for arbitrary d.Comment: 14 pages,latex,misprints in formulas 26,40,45 corrected,a reference adde

Feeling good about being hungry: food-related thoughts in eating disorder

Objectives: This study explores the relationships to food and hunger in women living with anorexic type eating difficulties and asks how imagery-based elaborations of food and eating thoughts are involved in their eating restraint, and recovery. Design: The qualitative idiographic approach of Interpretative Phenomenological Analysis (IPA) was used. Four in-depth semi-structured interviews were conducted with women self-selected as having experienced anorexia or anorexic like behaviour. Methods: The data was analysed using IPA and an audit of the analysis was conducted to ensure that the process followed had been systematic and rigorous and appropriately considered reflexivity. Results: Hunger was perceived positively by participants as confirmation that they were achieving their goal of losing weight, or avoiding weight gain. Hunger conferred a sense of being in control for the participants. Intrusive thoughts about food were reported as being quickly followed by elaborative mental imagery of the positive aspects of weight loss, and the negative consequences of eating. Imagery appeared to serve to maintain anorexic behaviours rather than to motivate food seeking. However, negative imagery of the consequences of anorexia were also described as supporting recovery. Conclusions: The finding that physiological sensations of hunger were experienced as positive confirmation of maintaining control has potentially important clinical and theoretical implications. It suggests further attention needs to be focused upon how changes in cognitive elaboration, involving mental imagery, are components of the psychological changes in the development of, maintenance of, and recovery from, anorexia

Type I D-branes in an H-flux and twisted KO-theory

Witten has argued that charges of Type I D-branes in the presence of an H-flux, take values in twisted KO-theory. We begin with the study of real bundle gerbes and their holonomy. We then introduce the notion of real bundle gerbe KO-theory which we establish is a geometric realization of twisted KO-theory. We examine the relation with twisted K-theory, the Chern character and provide some examples. We conclude with some open problems.Comment: 23 pages, Latex2e, 2 new references adde

Chronic performance of Riata 1580 and Endotak 0158 ICD leads: A single center 10-year experience

BACKGROUND: The long term performance of the Riata family of leads has recently come under increasing scrutiny. We aimed to determine the long term performance of the Riata 1580 leads compared with Endotak 0158 leads. METHODS: All patients with Riata 1580 or Endotak 0158 leads implanted from 2003-2008 at the Heart Hospital, UCLH were analysed. Significant electrical changes were: threshold increase >1V at a set pulse width between pacing checks, persistent R wave fall to 50%, noise, pacing impedance change to 1500 Ω, HV change to 200Ω, HV change ± 15Ω, pacing impedance change > 400Ω over 12 months. RESULTS: 333 Riata and 356 Endotak leads were implanted. Median follow up time + interquartile range, after exclusion of censored events including loss to follow up: Riata 3652 + 655 days, Endotak 3730 + 810 days. A total of 51 (15.9%) Riata leads and 21 (6.3%) Endotak leads were affected. A greater risk of failure was found for the Riata lead compared with the Endotak lead (p = 0.0001). An additional time-dependent effect was found, with the Riata lead 1.9 times more likely to fail in the first 6 years following lead implantation and 5.3 times more likely to fail after 6 years. CONCLUSIONS: Riata leads have a higher risk of failure compared to Endotak leads over time. The importance of careful ongoing performance surveillance late in the leads' lifetime is reflected in this ten year follow up study. This article is protected by copyright. All rights reserved

Lectures on mathematical aspects of (twisted) supersymmetric gauge theories

Supersymmetric gauge theories have played a central role in applications of quantum field theory to mathematics. Topologically twisted supersymmetric gauge theories often admit a rigorous mathematical description: for example, the Donaldson invariants of a 4-manifold can be interpreted as the correlation functions of a topologically twisted N=2 gauge theory. The aim of these lectures is to describe a mathematical formulation of partially-twisted supersymmetric gauge theories (in perturbation theory). These partially twisted theories are intermediate in complexity between the physical theory and the topologically twisted theories. Moreover, we will sketch how the operators of such a theory form a two complex dimensional analog of a vertex algebra. Finally, we will consider a deformation of the N=1 theory and discuss its relation to the Yangian, as explained in arXiv:1308.0370 and arXiv:1303.2632.Comment: Notes from a lecture series by the first author at the Les Houches Winter School on Mathematical Physics in 2012. To appear in the proceedings of this conference. Related to papers arXiv:1308.0370, arXiv:1303.2632, and arXiv:1111.423

Full density matrix dynamics for large quantum systems: Interactions, Decoherence and Inelastic effects

We develop analytical tools and numerical methods for time evolving the total density matrix of the finite-size Anderson model. The model is composed of two finite metal grains, each prepared in canonical states of differing chemical potential and connected through a single electronic level (quantum dot or impurity). Coulomb interactions are either excluded all together, or allowed on the dot only. We extend this basic model to emulate decoherring and inelastic scattering processes for the dot electrons with the probe technique. Three methods, originally developed to treat impurity dynamics, are augmented to yield global system dynamics: the quantum Langevin equation method, the well known fermionic trace formula, and an iterative path integral approach. The latter accommodates interactions on the dot in a numerically exact fashion. We apply the developed techniques to two open topics in nonequilibrium many-body physics: (i) We explore the role of many-body electron-electron repulsion effects on the dynamics of the system. Results, obtained using exact path integral simulations, are compared to mean-field quantum Langevin equation predictions. (ii) We analyze aspects of quantum equilibration and thermalization in large quantum systems using the probe technique, mimicking elastic-dephasing effects and inelastic interactions on the dot. Here, unitary simulations based on the fermionic trace formula are accompanied by quantum Langevin equation calculations

Asymmetric Heat Flow in Mesoscopic Magnetic System

The characteristics of heat flow in a coupled magnetic system are studied. The coupled system is composed of a gapped chain and a gapless chain. The system size is assumed to be quite small so that the mean free path is comparable to it. When the parameter set of the temperatures of reservoirs is exchanged, the characteristics of heat flow are studied with the Keldysh Green function technique. The asymmetry of current is found in the presence of a local equilibrium process at the contact between the magnetic systems. The present setup is realistic and such an effect will be observed in real experiments. We also discuss the simple phenomenological explanation to obtain the asymmetry.Comment: 13 pages, 3 figure