Transmission loss predictions for dissipative silencers of arbitrary cross section in the presence of mean flow

A numerical technique is developed for the analysis of dissipative silencers of arbitrary, but axially uniform, cross section. Mean gas flow is included in a central airway which is separated from a bulk reacting porous material by a concentric perforate screen. The analysis begins by employing the finite element method to extract the eigenvalues and associated eigenvectors for a silencer of infinite length. Point collocation is then used to match the expanded acoustic pressure and velocity fields in the silencer chamber to those in the inlet and outlet pipes. Transmission loss predictions are compared with experimental measurements taken for two automotive dissipative silencers with elliptical cross sections. Good agreement between prediction and experiment is observed both without mean flow and for a mean flow Mach number of 0.15. It is demonstrated also that the technique presented offers a considerable reduction in computational expenditure when compared to a three dimensional finite element analysis

Quasi-planar steep water waves

A new description for highly nonlinear potential water waves is suggested, where weak 3D effects are included as small corrections to exact 2D equations written in conformal variables. Contrary to the traditional approach, a small parameter in this theory is not the surface slope, but it is the ratio of a typical wave length to a large transversal scale along the second horizontal coordinate. A first-order correction for the Hamiltonian functional is calculated, and the corresponding equations of motion are derived for steep water waves over an arbitrary inhomogeneous quasi-1D bottom profile.Comment: revtex4, 4 pages, no figure

Bio-linguistic transition and Baldwin effect in an evolutionary naming-game model

We examine an evolutionary naming-game model where communicating agents are equipped with an evolutionarily selected learning ability. Such a coupling of biological and linguistic ingredients results in an abrupt transition: upon a small change of a model control parameter a poorly communicating group of linguistically unskilled agents transforms into almost perfectly communicating group with large learning abilities. When learning ability is kept fixed, the transition appears to be continuous. Genetic imprinting of the learning abilities proceeds via Baldwin effect: initially unskilled communicating agents learn a language and that creates a niche in which there is an evolutionary pressure for the increase of learning ability.Our model suggests that when linguistic (or cultural) processes became intensive enough, a transition took place where both linguistic performance and biological endowment of our species experienced an abrupt change that perhaps triggered the rapid expansion of human civilization.Comment: 7 pages, minor changes, accepted in Int.J.Mod.Phys.C, proceedings of Max Born Symp. Wroclaw (Poland), Sept. 2007. Java applet is available at http://spin.amu.edu.pl/~lipowski/biolin.html or http://www.amu.edu.pl/~lipowski/biolin.htm

Vasotocin receptor expression in the brain and pituitary gland during the ovulatory cycle of the fowl

Vasotocin receptors are members of seven transmembrane spanning G-protein associated receptors. Several isoforms have been recognized in mammals and birds. It has been shown that VT-1 expression occurs primarily in the brain while VT-2 expression occurs mainly in the pituitary. There is no current evidence to support that both VTR-1 and -2 are found in a single tissue. Our goal in this experiment was to see if VT-1 and VT-2 receptor mRNA expression varied in known sites of expression over the period of the ovulatory cycle of broiler breeder hens. In order to study potential changes in VT-1 and VT-2 expression, birds were sacrificed at 3 hour intervals over a 24 hour period. Blood samples were drawn. After cervical dislocation, the brain, pituitary, shell gland, and kidney were removed. Plasma was stored at -20ºC prior to determination of corticosterone levels by radioimmuno assays. Isolated mRNA from the brains and the pituitaries was transferred to nylon membranes for northern slot blot analysis. cDNA for VT-1 and VT-2 was used to make random primed cDNA probes. Corticosterone levels significantly increased at 9 hours post oviposition relative to all other times. Neither VT-1 or VT- 2 expression showed any significant variation over the 24 hour cycle. Based on these results, we conclude that VT-1 and VT-2 steady state mRNA levels do not fluctuate dramatically over the ovulatory cycle of broiler breeder hens. Further work on membrane bound receptors and on circadian variations in membrane bound receptors in the brain and pituitary is currently underway of broiler breeder hens

Concordance and Mutation

We provide a framework for studying the interplay between concordance and positive mutation and identify some of the basic structures relating the two. The fundamental result in understanding knot concordance is the structure theorem proved by Levine: for n>1 there is an isomorphism phi from the concordance group C_n of knotted (2n-1)-spheres in S^{2n+1} to an algebraically defined group G_{+-}; furthermore, G__{+-} is isomorphic to the infinite direct sum Z^infty direct sum Z_2^infty direct sum Z_4^infty. It was a startling consequence of the work of Casson and Gordon that in the classical case the kernel of phi on C_1 is infinitely generated. Beyond this, little has been discovered about the pair (C_1,phi). In this paper we present a new approach to studying C_1 by introducing a group, M, defined as the quotient of the set of knots by the equivalence relation generated by concordance and positive mutation, with group operation induced by connected sum. We prove there is a factorization of phi, C_1-->M-->G_-. Our main result is that both maps have infinitely generated kernels. Among geometric constructions on classical knots, the most subtle is positive mutation. Positive mutants are indistinguishable using classical abelian knot invariants as well as by such modern invariants as the Jones, Homfly or Kauffman polynomials. Distinguishing positive mutants up to concordance is a far more difficult problem; only one example has been known until now. The results in this paper provide, among other results, the first infinite families of knots that are distinct from their positive mutants, even up to concordance.Comment: Published in Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol5/paper26.abs.htm

Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies

We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effective yields of the less luminous half of our galaxy sample do not exceed 0.02 Z_sun, indicating that gas outflow is important in the chemical evolution of the less luminous galaxies. We surmise that the ratio of the importance of gas infall to gas outflow increases with galaxy luminosity. Strong correlations of average [Fe/H] and metallicity spread with luminosity support this hypothesis.Comment: 17 pages, 5 figures; accepted for publication in ApJ; minor corrections in v3; corrected typographical errors in Tables 1 and 3 in v

Progress in the development of an 88-mm bore 10 Tn3Sn dipole magnet

A 10 T, 2-layer cos(&thetas;)-dipole model magnet with an 88 mm clear bore utilizing an advanced powder-in-tube Nb3Sn conductor is being developed for the LHC. A dedicated conductor development program has resulted in a well performing Rutherford cable containing strands that uniquely exhibit both an overall current density of 600 A/mm2 @ 11 T and filaments with a diameter of 20 ¿m. The resistance between crossing strands amounts to 30-70 ¿¿ by insertion of a stainless steel core. After being exposed to a transverse pressure of 200 MPa identical cables show negligible permanent degradation of the critical current. The mechanical support structure is further optimized in order to reduce the peak stress in the mid-plane to below 130 MPa at full excitation and to control the pre-stress build-up during system assembly. Prior to the manufacturing of the final coils a dummy 2-layer pole is wound, heat-treated at 675°C and vacuum resin impregnated. This paper presents the current status of the magnet development program and highlights in particular the successful conductor developmen

Anion receptor chemistry: highlights from 2011 and 2012

This review covers advances in anion complexation in the years 2011 and 2012. The review covers both organic and inorganic systems and also highlights the applications to which anion receptors can be applied such as self-assembly and molecular architecture, sensing, catalysis and anion transport

Second-harmonic generation microscopy analysis reveals proteoglycan decorin is necessary for proper collagen organization in prostate.

Collagen remodeling occurs in many prostate pathologies; however, the underlying structural architecture in both normal and diseased prostatic tissues is largely unexplored. Here, we use second-harmonic generation (SHG) microscopy to specifically probe the role of the proteoglycan decorin (Dcn) on collagen assembly in a wild type (wt) and Dcn null mouse (Dcn  -    /    -  ). Dcn is required for proper organization of collagen fibrils as it regulates size by forming an arch-like structure at the end of the fibril. We have utilized SHG metrics based on emission directionality (forward-backward ratio) and relative conversion efficiency, which are both related to the SHG coherence length, and found more disordered fibril organization in the Dcn  -    /    -  . We have also used image analysis readouts based on entropy, multifractal dimension, and wavelet transforms to compare the collagen fibril/fiber architecture in the two models, where all these showed that the Dcn  -    /    -   prostate comprised smaller and more disorganized collagen structures. All these SHG metrics are consistent with decreased SHG phase matching in the Dcn  -    /    -   and are further consistent with ultrastructural analysis of collagen in this model in other tissues, which show a more random distribution of fibril sizes and their packing into fibers. As Dcn is a known tumor suppressor, this work forms the basis for future studies of collagen remodeling in both malignant and benign prostate disease