A new method for the separation of androgens from estrogens and for the partition of estriol from the estrone-estradiol fraction: with special reference to the identification and quantitative microdetermination of estrogens by ultraviolet absorption spectrophotometry

It is recognized generally that a qualitative and quantitative knowledge of the excretion pattern of the urinary estrogens is one index to an understanding of the functional activity of the ovary and adrenal cortex. Obviously, such determinations may be useful also in evaluating the normal and abnormal functions of other physiologically related endocrine glands as well as of organs like the liver and kidneys. The clinical applications of these data are self-evident. Various attempts have been made to circumvent the notoriously inaccurate values which have been obtained for the urinary estrogens by a variety of bioassay methods and calorimetric techniques (1, 2). The acknowledged shortcomings of these methods have led us to investigate the application of ultraviolet absorption spectrophotometry to the quantitative determination of the urinary estrogens in an attempt to develop an objective physical method for their accurate determination. It is known that the infra-red portion of the spectrum yields more differentially characteristic curves, but those of the ultraviolet range are more readily obtainable, and consequently better adapted to clinical use. This communication is concerned with studies of the following aspects of the problem: (1) spectrophotometric identification and quantitative micro determination of crystalline estrogens; (2) detection by spectrophotometric assay of gross errors in current methods for extraction and partition of estrogens; (3) studies on the ultraviolet absorption of substances comprising the background material; (4) separation of the phenolic estrogens from the so called neutral steroid fraction; (5) separation of urinary estrogens from other urinary phenolic substances by steam distillation; (6) micro-Girard separation of estrone from estradiol; (7) an essentially new method for the extraction and partition of crystalline estrone, estradiol, and estriol, and their quantitative assay by ultraviolet spectrophotometry

Morphine for cancer pain

CITATION: Smit, B. J. 1994. Morphine for cancer pain. South African Medical Journal, 84(11):788.The original publication is available at http://www.samj.org.za[No abstract available]Publisher’s versio

Simulations of Cold Electroweak Baryogenesis: Finite time quenches

The electroweak symmetry breaking transition may supply the appropriate out-of-equilibrium conditions for baryogenesis if it is triggered sufficiently fast. This can happen at the end of low-scale inflation, prompting baryogenesis to occur during tachyonic preheating of the Universe, when the potential energy of the inflaton is transfered into Standard Model particles. With the proper amount of CP-violation present, the observed baryon number asymmetry can be reproduced. Within this framework of Cold Electroweak Baryogenesis, we study the dependence of the generated baryon asymmetry on the speed of the quenching transition. We find that there is a separation between ``fast'' and ``slow'' quenches, which can be used to put bounds on the allowed Higgs-inflaton coupling. We also clarify the strong Higgs mass dependence of the asymmetry reported in a companion paper (hep-ph/0604263).Comment: 18 pages, 20 figure

Anomalous Hall Effect due to the spin chirality in the Kagom\'{e} lattice

We consider a model for a two dimensional electron gas moving on a kagom\'{e} lattice and locally coupled to a chiral magnetic texture. We show that the transverse conductivity $\sigma\_{xy}$ does not vanish even if spin-orbit coupling is not present and it may exhibit unusual behavior. Model parameters are the chirality, the number of conduction electrons and the amplitude of the local coupling. Upon varying these parameters, a topological transition characterized by change of the band Chern numbers occur. As a consequence, $\sigma\_{xy}$ can be quantized, proportional to the chirality or have a non monotonic behavior upon varying these parameters.Comment: 8 pages, 7 figure

Effective Use of Visualization in Education

With the ever increasing use of computers, visualization is used more and more. Powerpoint-fatigue is a well-known fact. There’s a general feeling that supportive technologies can be useful and effective in education, however those outcomes are often not achieved. Consequently people start to look for alternatives: movies, animations and infographics, have become common-practice. These are all powerful and valuable tools, also in education. It is very important though to ask what type of tool to use, for which kind of learning and to which purpose. In this article we attempt to derive a taxonomy which will help to make sound choices, so that visualization can be used effectively

Investigation of the Domain Wall Fermion Approach to Chiral Gauge Theories on the Lattice

We investigate a recent proposal to construct chiral gauge theories on the lattice using domain wall fermions. We restrict ourselves to the finite volume case, in which two domain walls are present, with modes of opposite chirality on each of them. We couple the chiral fermions on only one of the domain walls to a gauge field. In order to preserve gauge invariance, we have to add a scalar field, which gives rise to additional light mirror fermion and scalar modes. We argue that in an anomaly free model these extra modes would decouple if our model possesses a so-called strong coupling symmetric phase. However, our numerical results indicate that such a phase most probably does not exist. ---- Note: 9 Postscript figures are appended as uuencoded compressed tar file.Comment: 27p. Latex; UCSD/PTH 93-28, Wash. U. HEP/93-6

Phase diagram of patchy colloids: towards empty liquids

We report theoretical and numerical evaluations of the phase diagram for patchy colloidal particles of new generation. We show that the reduction of the number of bonded nearest neighbours offers the possibility of generating liquid states (i.e. states with temperature $T$ lower than the liquid-gas critical temperature) with a vanishing occupied packing fraction ($\phi$), a case which can not be realized with spherically interacting particles. Theoretical results suggest that such reduction is accompanied by an increase of the region of stability of the liquid phase in the ($T$-$\phi$) plane, possibly favoring the establishment of homogeneous disordered materials at small $\phi$, i.e. stable equilibrium gels.Comment: 4 pages, 4 figures, revised version, accepted in Phys. Rev. Let

Anomalous Hall Effect in Ferromagnetic Semiconductors in the Hopping Transport Regime

We present a theory of the Anomalous Hall Effect (AHE) in ferromagnetic (Ga,Mn)As in the regime when conduction is due to phonon-assisted hopping of holes between localized states in the impurity band. We show that the microscopic origin of the anomalous Hall conductivity in this system can be attributed to a phase that a hole gains when hopping around closed-loop paths in the presence of spin-orbit interactions and background magnetization of the localized Mn moments. Mapping the problem to a random resistor network, we derive an analytic expression for the macroscopic anomalous Hall conductivity $\sigma_{xy}^{AH}$. We show that $\sigma_{xy}^{AH}$ is proportional to the first derivative of the density of states $\varrho(\epsilon)$ and thus can be expected to change sign as a function of impurity band filling. We also show that $\sigma_{xy}^{AH}$ depends on temperature as the longitudinal conductivity $\sigma_{xx}$ within logarithmic accuracy.Comment: 4 pages, 1 eps figure, final versio

Phase Coexistence of a Stockmayer Fluid in an Applied Field

We examine two aspects of Stockmayer fluids which consists of point dipoles that additionally interact via an attractive Lennard-Jones potential. We perform Monte Carlo simulations to examine the effect of an applied field on the liquid-gas phase coexistence and show that a magnetic fluid phase does exist in the absence of an applied field. As part of the search for the magnetic fluid phase, we perform Gibbs ensemble simulations to determine phase coexistence curves at large dipole moments, $\mu$. The critical temperature is found to depend linearly on $\mu^2$ for intermediate values of $\mu$ beyond the initial nonlinear behavior near $\mu=0$ and less than the $\mu$ where no liquid-gas phase coexistence has been found. For phase coexistence in an applied field, the critical temperatures as a function of the applied field for two different $\mu$ are mapped onto a single curve. The critical densities hardly change as a function of applied field. We also verify that in an applied field the liquid droplets within the two phase coexistence region become elongated in the direction of the field.Comment: 23 pages, ReVTeX, 7 figure

Localized Control of Curie Temperature in Perovskite Oxide Film by Capping-layer- induced Octahedral Distortion

With reduced dimensionality, it is often easier to modify the properties of ultra-thin films than their bulk counterparts. Strain engineering, usually achieved by choosing appropriate substrates, has been proven effective in controlling the properties of perovskite oxide films. An emerging alternative route for developing new multifunctional perovskite is by modification of the oxygen octahedral structure. Here we report the control of structural oxygen octahedral rotation in ultra-thin perovskite SrRuO3 films by the deposition of a SrTiO3 capping layer, which can be lithographically patterned to achieve local control. Using a scanning Sagnac magnetic microscope, we show increase in the Curie temperature of SrRuO3 due to the suppression octahedral rotations revealed by the synchrotron x-ray diffraction. This capping-layer-based technique may open new possibilities for developing functional oxide materials.Comment: Main-text 5 pages, SI 6 pages. To appear in Physical Review Letter