Streptomycin: A Review of the Literature

Streptomycin is an antibacterial agent of relatively low toxicity which was isolated by Selman A. Waksman in 1944 from certain strains of the soil actinomycete, Streptomyces grieseus

Problems Encountered in an Ovine Practice

With the increase in the number of farm flocks, sheep have assumed an ever increasing role in veterinary practice. It has been said, and justly so, that a sheep is a difficult animal to treat. However, with the improvement in vaccines and pharmaceuticals, excellent results may be obtained if the original diagnosis is correct. With sheep, perhaps more than any other animal, a correct diagnosis is essential to successful treatment. A mistaken diagnosis and subsequent erroneous treatment may be disastrous

Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP

We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat cosmological constant dominated cosmological model. Analyses of the simulated MAP data at 90 GHz (0.3 deg FWHM resolution smoothed) show that foreground effects on the correlation function are small compared with cosmic variance. However, the Galactic emission, even just from the region with |b| > 20 deg, significantly affects the topology of CMB anisotropy, causing a negative genus shift non-Gaussianity signal. Given the expected level of cosmic variance, this effect can be effectively reduced by subtracting existing Galactic foreground emission models from the observed data. IRAS and DIRBE far-infrared extragalactic sources have little effect on the CMB anisotropy. Radio point sources raise the amplitude of the correlation function considerably on scales below 0.5 deg. Removal of bright radio sources above a 5 \sigma detection limit effectively eliminates this effect. Radio sources also result in a positive genus curve asymmetry (significant at 2 \sigma) on 0.5 deg scales. Accurate radio point source data is essential for an unambiguous detection of CMB anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological origin can be detected from the foreground-subtracted CMB anisotropy map at the 2 \sigma level if the measured genus shift parameter |\Delta\nu| >= 0.02 (0.04) or if the measured genus asymmetry parameter |\Delta g| >= 0.03 (0.08) on a 0.3 (1.0) deg FWHM scale.Comment: 26 pages, 7 figures, Accepted for Publication in Astrophysical Journal (Some sentences and figures modified

Getting the Measure of the Flatness Problem

The problem of estimating cosmological parameters such as $\Omega$ from noisy or incomplete data is an example of an inverse problem and, as such, generally requires a probablistic approach. We adopt the Bayesian interpretation of probability for such problems and stress the connection between probability and information which this approach makes explicit. This connection is important even when information is ``minimal'' or, in other words, when we need to argue from a state of maximum ignorance. We use the transformation group method of Jaynes to assign minimally--informative prior probability measure for cosmological parameters in the simple example of a dust Friedman model, showing that the usual statements of the cosmological flatness problem are based on an inappropriate choice of prior. We further demonstrate that, in the framework of a classical cosmological model, there is no flatness problem.Comment: 11 pages, submitted to Classical and Quantum Gravity, Tex source file, no figur

The Pragmatic Vision of Visionary Pragmatism: The Challenge of Radical Democracy in a Neoliberal World Order

Visionary Pragmatism is a project formulated in the face of a hyper-malignant mode of capitalism that is provoking and entangled with ecological collapse, dedemocratization, unfathomable inequality, destruction of the commons, intensifying xenophobia, and racism. In the book, I seek modes of radical and ecological democracy that advance beyond both modest resistance and radical posturing that is largely empty and formulaic. I explore possibilities for generating new political modes in a variety of locations, and especially at the intersections where democratic initiatives in higher education engage with myriad publics to intensify alternative processes of knowledge production, political practice, and power that are sufficiently game-transformative in their own right to stand a chance of generating radical change. Beyond myopic pragmatism and hyper-professionalized scholarship, ‘visionary pragmatism’ offers a path along which we might refashion more imaginative theory through modes of creatively engaged practice and, in turn, more radical politics in conjunction with theory thus generated and critical theory broadly construed. Stylistically, the book moves between theoretical reflection and ethnography

Modeling temporal fluctuations in avalanching systems

We demonstrate how to model the toppling activity in avalanching systems by stochastic differential equations (SDEs). The theory is developed as a generalization of the classical mean field approach to sandpile dynamics by formulating it as a generalization of Itoh's SDE. This equation contains a fractional Gaussian noise term representing the branching of an avalanche into small active clusters, and a drift term reflecting the tendency for small avalanches to grow and large avalanches to be constricted by the finite system size. If one defines avalanching to take place when the toppling activity exceeds a certain threshold the stochastic model allows us to compute the avalanche exponents in the continum limit as functions of the Hurst exponent of the noise. The results are found to agree well with numerical simulations in the Bak-Tang-Wiesenfeld and Zhang sandpile models. The stochastic model also provides a method for computing the probability density functions of the fluctuations in the toppling activity itself. We show that the sandpiles do not belong to the class of phenomena giving rise to universal non-Gaussian probability density functions for the global activity. Moreover, we demonstrate essential differences between the fluctuations of total kinetic energy in a two-dimensional turbulence simulation and the toppling activity in sandpiles.Comment: 14 pages, 11 figure

The impact of surface roughness geometry on aero-engine intakes at incidence

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Shock Wave-Boundary-Layer Interactions, or SBLI’s, are known to form on engine inlets within a complex transonic flow-field during typical take-off and climb configurations. On the engine inlet, there are a number of potential sources of surface roughness, such as novel de-icing and acoustic systems, or surface contamination. The impact on the flow-field structure, as a result of this roughness, may lead to detrimental side effects, such as losses in engine efficiency or intake flow stability. Previous research into two-dimensional roughness shapes demonstrated flow-field changes, for example a thicker downstream-boundary layer compared to a smooth surface. This paper compares the impact of a two-dimensional ridge roughness to a three-dimensional cubed roughness on the inlet flow-field. The effect of these rough surfaces is examined with schlieren photography and Laser Doppler Velocime-try (LDV) techniques. At an on-design condition, a rough surface promotes a smaller supersonic region, and a thicker boundary-layer downstream of the interaction compared to a smooth surface. At off-design upper surface mass flow rate conditions, modelling a higher mass flow engine demand, the supersonic region grows, leading to a shock location further downstream. Under these conditions, roughness also promotes a thicker downstream boundary-layer. However, comparing the two-dimensional with three-dimensional roughness at an approximate fan-face location, shows that three-dimensional roughness is more benign for all off-design cases. This suggests that the topology of the roughness is influencing the condition of the boundary-layer at this location

The quantum inflaton, primordial perturbations and CMB fluctuations

We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the dynamics of the (classical) cosmological metric. For chaotic inflation, the quantum treatment avoids the unnatural requirements of an initial state with all the energy in the zero mode. For new inflation it allows a consistent treatment of the explosive particle production due to spinodal instabilities. Quantum field inflation (under conditions that are the quantum analog of slow roll) leads, upon evolution, to the formation of a condensate starting a regime of effective classical inflation. We compute the primordial perturbations taking the dominant quantum effects into account. The results for the scalar, vector and tensor primordial perturbations are expressed in terms of the classical inflation results. For a N-component field in a O(N) symmetric model, adiabatic fluctuations dominate while isocurvature or entropy fluctuations are negligible. The results agree with the current WMAP observations and predict corrections to the power spectrum in classical inflation.Such corrections are estimated to be of the order of m^2/[N H^2] where m is the inflaton mass and H the Hubble constant at horizon crossing. This turns to be about 4% for the cosmologically relevant scales. This quantum field treatment of inflation provides the foundations to the classical inflation and permits to compute quantum corrections to it.Comment: 23 pages, no figures. Improved version to appear in Phys. Rev.

Stochastic Biasing and Weakly Non-linear Evolution of Power Spectrum

Distribution of galaxies may be a biased tracer of the dark matter distribution and the relation between the galaxies and the total mass may be stochastic, non-linear and time-dependent. Since many observations of galaxy clustering will be done at high redshift, the time evolution of non-linear stochastic biasing would play a crucial role for the data analysis of the future sky surveys. In this paper, we develop the weakly non-linear analysis and attempt to clarify the non-linear feature of the stochastic biasing. We compute the one-loop correction of the power spectrum for the total mass, the galaxies and their cross correlation. Assuming the local functional form for the initial galaxy distribution, we investigate the time evolution of the biasing parameter and the correlation coefficient. On large scales, we first find that the time evolution of the biasing parameter could deviate from the linear prediction in presence of the initial skewness. However, the deviation can be reduced when the initial stochasticity exists. Next, we focus on the quasi-linear scales, where the non-linear growth of the total mass becomes important. It is recognized that the scale-dependence of the biasing dynamically appears and the initial stochasticity could affect the time evolution of the scale-dependence. The result is compared with the recent N-body simulation that the scale-dependence of the halo biasing can appear on relatively large scales and the biasing parameter takes the lower value on smaller scales. Qualitatively, our weakly non-linear results can explain this trend if the halo-mass biasing relation has the large scatter at high redshift.Comment: 29pages, 7 postscript figures, submitted to Ap

Perturbative Analysis of Adaptive Smoothing Methods in Quantifying Large-Scale Structure

Smoothing operation to make continuous density field from observed point-like distribution of galaxies is crucially important for topological or morphological analysis of the large-scale structure, such as, the genus statistics or the area statistics (equivalently the level crossing statistics). It has been pointed out that the adaptive smoothing filters are more efficient tools to resolve cosmic structures than the traditional spatially fixed filters. We study weakly nonlinear effects caused by two representative adaptive methods often used in smoothed hydrodynamical particle (SPH) simulations. Using framework of second-order perturbation theory, we calculate the generalized skewness parameters for the adaptive methods in the case of initially power-law fluctuations. Then we apply the multidimensional Edgeworth expansion method and investigate weakly nonlinear evolution of the genus statistics and the area statistics. Isodensity contour surfaces are often parameterized by the volume fraction of the regions above a given density threshold. We also discuss this parameterization method in perturbative manner.Comment: 42 pages including 9 figure, ApJ 537 in pres