New Synonymies and Combinations for New World Pselaphinae (Coleoptera: Staphylinidae)

The following new synonymies and new combinations for Pselaphinae of North and Central America are documented: Anarmodius aequinoctialis (Motschulsky) (Trichonyx), New Comb.; Anthylarthron cornutum (Brendel) (= Anthylarthron curtipenne Casey, New Syn.); Aporhexius robustus (Motschulsky) (Euplectus), New Comb.; Batrisodespunctlfrons Casey (= Batrisodes appalachianus Casey, New Syn.); Batrisodes ionae (LeConte) (= Batrisodes caseyt Blatchley, New Syn.); Batrisodes clypeonotus (Brendel) (= Batrisodes kahli Bowman, New Syn.); Batrisodes lineaticollis (Aube) (= Batrisus globosus LeConte, New Syn.); Brachygluta corniventris (Motschulsky) (Bryaxts), New Comb., (= Bryaxts illinoiensis Brendel, New Syn.); Cedius ziegleri LeConte (= Cedius robustus Casey, New Syn.); Conoplectus simplex (Motschulsky) (Rhexius), New Comb., jun. syn. of Conoplectus canaliculatus (LeConte), New Syn.; Ctenisodes Raffray (= Pilopius Casey, New Syn.); Cylindrarctus ludovicianus (Brendel) (= Cylindrarctus comes Casey, New Syn.; Dalmosanus Park (= Pygmactium Grigarick and Schuster, New Syn.); Decarthron consanguineum (Motschulsky) (Bryaxis), New Comb.; Decarthron formiceti (LeConte) (= Decarthron rayi Park, = Decarthron seriepunctatum Brendel, New Syns.); Decarthron velutinum (LeConte), New Status (= D. formiceti, Park, 1958); Decarthron marinum Brendel (= Decarthron diversum Park, New Syn.); Decarthron robustum (Motschulsky) (Metaxis), New Comb.; Euphalepsus Reitter (= Barada Raffray, = Tetrasemus Jeannel, New Syns.), in subtribe Baradina; Eupsentus dilatatus Motschulsky (= Eupsenius rufus LeConte, New Syn.); Eurhexius canaliculatus (Motschulsky) (Trichonyx), New Comb. (= Eurhexius zonalis Park, New Syn.); Harmophola adusta (Motschulsky) (Euplectus), New Comb.; Iteticus cylindricus (Motschulsky) (Batrisus), New Comb.; Nisaxis Casey (=Dranisaxa Park, New Syn.); Oropus strtatus (LeConte) (=Oropus keeni Casey and O. brevipennis Casey, New Syns.); Panaramecia tropicalis (Motschulsky) (Euplectus), New Comb. (= Panaramecia zvilliamsi Park, New Syn.); Phamisus Aube, (= Canthoderus Motschulsky, New Syn.); Pselaptus oedipus (Sharp) (Bryaxis, Cryptorhinula), New Comb.; Pselaphus bellax Casey (= Pselaphus ulkei Bowman, New Syn); Reichenbachia intacta (Sharp) (= Bryaxis sarcinaria Schaufuss, New Syn.); Reichenbachia pruinosa (Motschulsky) (Bryaxis), New Comb., (= Bryaxis macrura Motschulsky, = Reichenbachia bterigi Park, New Syns.); Reichenbachia rubricunda (Aube) (= Bryaxis gemmifer LeConte, New Syn.); Trimicerus Motschulsky, (= Batrybraxis Reitter, New Syn.); Trimicerus corn?gera (Motschulsky) (Bryaxis), New Comb. (= Batrybraxis panamensis Park, New Syn.); Trimicerus pacificus Motschulsky (= Batrybraxis bowmani Park, New Syn.); Trimiomelba dubia (LeConte) (= Trimium americanum Motschulsky, = Trimium convexulum LeConte, = Trimiomelba laevis Casey, New Syns.); Tyrus humeralis (Aube) (= Tyrus consimilis Casey, New Syn.); Tyrus semiruber Casey (= Tyrus humeralis of authors); Tyrus cortidnus Casey (= Tyrus carinifer Casey, New Syn.); Xybarida trimioides (Sharp) (Bryaxis, Cryptorhinula), New Comb. Lectotype designations: Batrisus ionae LeConte; Batrisus globosus LeConte; Bryaxis consangu?nea Motschulsky; Bryaxis corniventris Motschulsky; Bryaxis pruinosa Motschulsky; Metaxis robusta Motschulsky; Rhextus simplex Motschulsky; Trimium americanum LeConte; Tyrus consimilis Casey. New species and genera: Cylindrarctus semin?le Chandler, New Species (= Cylindrarctus comes, Chandler, 1988); Motschtyrus pilosus (Motschulsky) (Tychus), Panama, New Genus, New Comb

A wavenumber independent boundary element method for an acoustic scattering problem

In this paper we consider the impedance boundary value problem for the Helmholtz equation in a half-plane with piecewise constant boundary data, a problem which models, for example, outdoor sound propagation over inhomogeneous. at terrain. To achieve good approximation at high frequencies with a relatively low number of degrees of freedom, we propose a novel Galerkin boundary element method, using a graded mesh with smaller elements adjacent to discontinuities in impedance and a special set of basis functions so that, on each element, the approximation space contains polynomials ( of degree.) multiplied by traces of plane waves on the boundary. We prove stability and convergence and show that the error in computing the total acoustic field is O( N-(v+1) log(1/2) N), where the number of degrees of freedom is proportional to N logN. This error estimate is independent of the wavenumber, and thus the number of degrees of freedom required to achieve a prescribed level of accuracy does not increase as the wavenumber tends to infinity

A frequency-independent boundary element method for scattering by two-dimensional screens and apertures

We propose and analyse a hybrid numerical-asymptotic $hp$ boundary element method for time-harmonic scattering of an incident plane wave by an arbitrary collinear array of sound-soft two-dimensional screens. Our method uses an approximation space enriched with oscillatory basis functions, chosen to capture the high frequency asymptotics of the solution. Our numerical results suggest that fi�xed accuracy can be achieved at arbitrarily high frequencies with a frequency-independent computational cost. Our analysis does not capture this observed behaviour completely, but we provide a rigorous frequency-explicit error analysis which proves that the method converges exponentially as the number of degrees of freedom $N$ increases, and that to achieve any desired accuracy it is sufficient to increase $N$ in proportion to the square of the logarithm of the frequency as the frequency increases (standard boundary element methods require $N$ to increase at least linearly with frequency to retain accuracy). We also show how our method can be applied to the complementary "breakwater" problem of propagation through an aperture in an infinite sound-hard screen

Exhaust cloud rise and diffusion in the atmosphere

Analytical approach develops physical-mathematical model of rocket engine exhaust cloud rise, growth, and diffusion. Analytic derivations and resultant model apply to hot exhaust cloud study or industrial stack plumes, making work results applicable to air pollution. Model formulations apply to all exhaust cloud types and various atmospheric conditions

Convergence analysis of a multigrid algorithm for the acoustic single layer equation

We present and analyze a multigrid algorithm for the acoustic single layer equation in two dimensions. The boundary element formulation of the equation is based on piecewise constant test functions and we make use of a weak inner product in the multigrid scheme as proposed in \cite{BLP94}. A full error analysis of the algorithm is presented. We also conduct a numerical study of the effect of the weak inner product on the oscillatory behavior of the eigenfunctions for the Laplace single layer operator

Posthumous Resilience and Active Withdrawal: Byronic Contemplation of Violence and Vulnerabilities in the Anthropocene Embodied in the Sculpture of the Dying Gaul

This paper focuses upon the famous sculpture of the Dying Gaul, situated in the Capitoline Museum in Rome, in order to read and to rethink discourses of resilience in the Anthropocene. The Anthropocene poses fundamental questions to understandings of ‘bouncing back’ or imaginaries of ‘sustainable futures’. There can be no affirmative futural imaginaries if saving the world requires the destruction and sacrifice of innumerable others. Thinking with Byron’s reflections upon the Dying Gaul enables us to approach resilience from a radically different perspective, one that (read in conjunction with the work of Claire Colebrook, Karen Barad, Christina Sharpe, Dionne Brand and Saidiya Hartman amongst other contemporary theorists) we call a ‘posthumous’ approach. ‘Posthumous resilience’ refuses the lure of affirmation, of imaginaries of salvage and salvation, and instead seeks to generate an ethic of ‘active withdrawal’ that points beyond the temporal and spatial constraints of the colonial, imperial, imagination. We conclude with a reflection on how posthumous discourses of ‘active withdrawal’ can be the basis of generative politics of refusal which hold open conceptions of justice and seek to break from cycles of violence

An integral equation method for a boundary value problem arising in unsteady water wave problems

In this paper we consider the 2D Dirichlet boundary value problem for Laplace’s equation in a non-locally perturbed half-plane, with data in the space of bounded and continuous functions. We show uniqueness of solution, using standard Phragmen-Lindelof arguments. The main result is to propose a boundary integral equation formulation, to prove equivalence with the boundary value problem, and to show that the integral equation is well posed by applying a recent partial generalisation of the Fredholm alternative in Arens et al [J. Int. Equ. Appl. 15 (2003) pp. 1-35]. This then leads to an existence proof for the boundary value problem. Keywords. Boundary integral equation method, Water waves, Laplace’