Criticality in confined ionic fluids

A theory of a confined two dimensional electrolyte is presented. The positive and negative ions, interacting by a $1/r$ potential, are constrained to move on an interface separating two solvents with dielectric constants $\epsilon_1$ and $\epsilon_2$. It is shown that the Debye-H\"uckel type of theory predicts that the this 2d Coulomb fluid should undergo a phase separation into a coexisting liquid (high density) and gas (low density) phases. We argue, however, that the formation of polymer-like chains of alternating positive and negative ions can prevent this phase transition from taking place.Comment: RevTex, no figures, in press Phys. Rev.

A stochastic model for heart rate fluctuations

Normal human heart rate shows complex fluctuations in time, which is natural, since heart rate is controlled by a large number of different feedback control loops. These unpredictable fluctuations have been shown to display fractal dynamics, long-term correlations, and 1/f noise. These characterizations are statistical and they have been widely studied and used, but much less is known about the detailed time evolution (dynamics) of the heart rate control mechanism. Here we show that a simple one-dimensional Langevin-type stochastic difference equation can accurately model the heart rate fluctuations in a time scale from minutes to hours. The model consists of a deterministic nonlinear part and a stochastic part typical to Gaussian noise, and both parts can be directly determined from the measured heart rate data. Studies of 27 healthy subjects reveal that in most cases the deterministic part has a form typically seen in bistable systems: there are two stable fixed points and one unstable one.Comment: 8 pages in PDF, Revtex style. Added more dat

The resultant on compact Riemann surfaces

We introduce a notion of resultant of two meromorphic functions on a compact Riemann surface and demonstrate its usefulness in several respects. For example, we exhibit several integral formulas for the resultant, relate it to potential theory and give explicit formulas for the algebraic dependence between two meromorphic functions on a compact Riemann surface. As a particular application, the exponential transform of a quadrature domain in the complex plane is expressed in terms of the resultant of two meromorphic functions on the Schottky double of the domain.Comment: 44 page

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

The in vitro induction and release of a cell toxin by immune C57B1-6 mouse peritoneal macrophages.

Peritoneal macrophages from Sarcoma 1 (SAl)-sensitized CS7B1/6 mice release a toxic factor (s), termed macrophage toxic factor (MTF), into the medium when exposed to allogeneic target L cells in vitro. Medium containing MTF is cytotoxic to cultures of allogeneic L cells, syngeneic C57B1/6 fetal fibroblasts and xenogenic HeLa cells. The cell toxin (s) is insensitive to the effects of nuclease, neuraminidase and trypsin, but is partially abrogated by treatment with pronase. Two fractions of toxic activity are eluted from Sephadex G-100, one associated with a 150,000 mol wt marker (IgG), and the other associated with a 47,000 mol wt marker (ovalbumin). Goat antiserum prepared against PHA-induced mouse lymphotoxin (MLT) is capable of neutralizing the toxicity of both MTF and MLT, indicating that the factors may be similar. © 1972

Polygeneration of Fischer-Tropsch fuels and electricity by hybridised solar gasification of coal - a pseudo-dynamic process model

Presented is a comparative energetic and environmental performance analysis of a solar hybridised gasification, coal to liquids polygeneration system and a non-solar reference. Using AspenPlus and HYSYS software, the reference system was configured, assuming the integration of a pressurised, Shell entrained flow gasifier with a Fischer Tropsch liquids (FTL) polygeneration facility. The hybrid plant assumes the feasibility of integrating an atmospheric, continuously operational, directly irradiated, oxygen blown hybrid solar reactor with this polygeneration facility. To mitigate the diurnal and stochastic impacts of the solar-boosted production of syngas, the hybrid polygeneration model was also assumed to be configured with a pressurised syngas storage plant. Here, the dynamic operation of the polygeneration system was modeled using a pseudo-steady state approximation for two, six day time-series of validated solar insolation model data. The two time-series were selected to represent a period in 'summer' characterised by a steady, low cloud period of solar insolation, and a period in 'winter' marked by intermittent solar insolation and high cloud. Using these data, a MATLAB model was used to predict the maximum steady rate of liquids that could be produced for the given solar insolation scenario. For the summer time series, the hybrid solar gasification system was shown to improve the steady rate of liquids production by 32% and decrease the source-to-wheel (STW) GHG emissions per GJ FTL by 26%, relative to the reference. For the winter time-series, only a marginal improvement in liquids production was predicted .This result followed from the assumed difference in gasification temperatures between the hybrid system and the reference. On a total energetic output basis, GHG emissions were shown to decrease relative to the reference by 17-21 percentage points for the summer-time series, but increase by 18 percentage points for the winter time-series. This increase in GHG emissions follows the large parasitic impact of SG compression on the hybrid system's net electrical output. Additional sensitivity analyses identified the potentially significant energetic and environmental value of either operating the hybrid gasifier at just 2 bar-g instead of 1 bar-g or incorporating an O2 storage system to reduce the parasitic load of the hybrid system's ASU. Importantly, the present analysis found the difference in the steady output from the FT reactor and electricity generating plant between the summer and winter time-series to be within the feasible operational limits of the respective plant components. This provides assurance as to the feasibility of developing a solar hybridised C2L polygeneration facility using commercially available plant components.Ashok A Kaniyal, Philip J van Eyk, Graham J Nathan, Peter J Ashman, Jonathan J Pincu