On the homotopy invariance of configuration spaces

For a closed PL manifold M, we consider the configuration space F(M,k) of ordered k-tuples of distinct points in M. We show that a suitable iterated suspension of F(M,k) is a homotopy invariant of M. The number of suspensions we require depends on three parameters: the number of points k, the dimension of M and the connectivity of M. Our proof uses a mixture of Poincare embedding theory and fiberwise algebraic topology.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-35.abs.htm

Laser ignition of iso-octane air aerosols

Iso-octane aerosols in air have been ignited with a focused Nd:YAG laser at pressures and temperatures of 100kPa and 270K and imaged using schlieren photography. The aerosol was generated using the Wilson cloud chamber technique. The droplet diameter, gas phase equivalence ratio and droplet number density were determined. The input laser energy and overall equivalence ratio were varied. For 270mJ pulse energies initial breakdown occurred at a number of sites along the laser beam axis. From measurements of the shock wave velocity it was found that energy was not deposited into the sites evenly. At pulse energies of 32mJ a single ignition site was observed. Overall fuel lean flames were observed to locally extinguish, however both stoichiometric and fuel rich flames were ignited. The minimum ignition energy was found to depend on the likelihood of a droplet existing at the focus of the laser beam

Higher-dimensional black holes with a conformally invariant Maxwell source

We consider an action for an abelian gauge field for which the density is given by a power of the Maxwell Lagrangian. In d spacetime dimensions this action is shown to enjoy the conformal invariance if the power is chosen as d/4. We take advantage of this conformal invariance to derive black hole solutions electrically charged with a purely radial electric field. Because of considering power of the Maxwell density, the black hole solutions exist only for dimensions which are multiples of four. The expression of the electric field does not depend on the dimension and corresponds to the four-dimensional Reissner-Nordstrom field. Using the Hamiltonian action we identify the mass and the electric charge of these black hole solutions.Comment: 5 page

Pengaruh Pelatihan terhadap Kompetensi (Penelitian Tentang Pelatihan pada Calon Tenaga Kerja Indonesia di PT Tritama Bina Karya Malang)

The aim of this research is to know the influence of the variables of Training Method (X1), Training Material (X2), Training Instructor (X3) on Labor Competence (Y) simultaneously and partially. This type of training is explanatory research (explanation) with quantitative approach and conducted by questionnaire method. This research is done by giving a written question to all employees of PT Tritama Bina Karya Malang distribution of labor services which amounted to 106 people and located Ki Ageng Gribig street Kedungkandang, Malang City. Data analysis technique used is descriptive analysis and multiple linear regression analysis with F (simultaneous) and t test (partial). Based on F test, it can be seen that F arithmetic> F table is 46,439> 2,694 or sig value. F (0,000) <α = 0.05 then the regression analysis model is significant because H0 is rejected and H1 is accepted. So it can be concluded that the dependent variable (Labor Competence) can be significantly affected by the independent variables of Training Methods, Training Materials, and Training Instructors simultaneously. Based on t test results it can be seen that each independent variable (Training Method, Training Material, and Training Instructor) has a partially significant influence on the dependent variable (Labor Competency). Kеywords: Training Methods, Training Materials, Training Instructors and Labor Competencies АBSTRАK Jenis pelatihan ini adalah explanatory research (penjelasan) dengan pendekatan kuantitatif dan dilakukan dengan metode kuesioner. Penelitian ini dilakukan dengan memberikan seperangkat pertanyaan tertulis kepada seluruh tenaga kerja PT Tritama Bina Karya Malang penyaluran jasa tenaga kerja yang berjumlah 106 orang dan berlokasi jalan Ki Ageng Gribig Kedungkandang, Kota Malang. Teknik analisis data yang digunakan adalah analisis deskriptif dan analisis regresi linier berganda dengan uji F (simultan) dan uji t (parsial). Berdasarkan uji F yang dilakukan dapat diketahui bahwa F hitung>F tabel yaitu 46,439 > 2,694 atau nilai sig. F (0,000) < α = 0.05 maka model analisis regresi adalah signifikan karena H0 ditolak dan H1 diterima. Jadi dapat disimpulkan bahwa variabel terikat (Kompetensi Tenaga Kerja) dapat dipengaruhi secara signifikan oleh variabel bebas Metode Pelatihan, Materi Pelatihan, dan Instruktur Pelatihan secara simultan. Berdasarkan hasil uji t dapat diketahui bahwa masing-masing variabel bebas (Metode Pelatihan, Materi Pelatihan, dan Instruktur Pelatihan) mempunyai pengaruh yang signifikan secara parsial terhadap variabel terikat (Kompetensi Tenaga Kerja). Kаtа Kunci: Metode Pelatihan, Materi Pelatihan, Instruktur Pelatihan dan Kompetensi Tenaga Kerj

Analogies between self-duality and stealth matter source

We consider the problem of a self-interacting scalar field nonminimally coupled to the three-dimensional BTZ metric such that its energy-momentum tensor evaluated on the BTZ metric vanishes. We prove that this system is equivalent to a self-dual system composed by a set of two first-order equations. The self-dual point is achieved by fixing one of the coupling constant of the potential in terms of the nonminimal coupling parameter. At the self-dual point and up to some boundary terms, the matter action evaluated on the BTZ metric is bounded below and above. These two bounds are saturated simultaneously yielding to a vanishing action for configurations satisfying the set of self-dual first-order equations.Comment: 6 pages. To be published in Jour. Phys.

Invariant density and time asymptotics for collisionless kinetic equations with partly diffuse boundary operators

International audienceThis paper deals with collisionless transport equationsin bounded open domains $\Omega \subset \R^{d}$ $(d\geq 2)$ with $\mathcal{C}^{1}$ boundary $\partial \Omega$, orthogonallyinvariant velocity measure \bm{m}(\d v) with support $V\subset \R^{d}$ and stochastic partly diffuse boundary operators $\mathsf{H}$ relating the outgoing andincoming fluxes. Under very general conditions, such equations are governedby stochastic $C_{0}$-semigroups $\left( U_{\mathsf{H}}(t)\right) _{t\geq 0}$ on $$ We give a general criterion of irreducibility of $$ and we show that, under very natural assumptions, if an invariant densityexists then $\left( U_{\mathsf{H}}(t)\right) _{t\geq 0}$ converges strongly (notsimply in Cesar\`o means) to its ergodic projection. We show also that if noinvariant density exists then $\left( U_{\mathsf{H}}(t)\right) _{t\geq 0}$ is\emph{sweeping} in the sense that, for any density $\varphi$, the total mass of $$ concentrates near suitable sets of zero measure as $$ We show also a general weak compactness theoremwhich provides a basis for a general theory on existence of invariantdensities. This theorem is based on a series of results on smoothness andtransversality of the dynamical flow associated to $\left( U_{\mathsf{H}}(t)\right) _{t\geq0}.

Dominant Energy Condition and dissipative fluids in general relativity

Existing literature implements the Dominant Energy Condition for dissipative fluids in general relativity. It is pointed out that this condition fails to forbid superluminal flows, which is what it is ultimately supposed to do. Tilted perfect fluids, which formally have the stress-energy tensor of imperfect fluids, are discussed for comparison.Comment: Corrected typographical error in Eq. (31). Matches the version to appear in Gen. Relativ. Gravi

Dynamic stability of crack fronts: Out-of-plane corrugations

The dynamics and stability of brittle cracks are not yet fully understood. Here we use the Willis-Movchan 3D linear perturbation formalism [J. Mech. Phys. Solids {\bf 45}, 591 (1997)] to study the out-of-plane stability of planar crack fronts in the framework of linear elastic fracture mechanics. We discuss a minimal scenario in which linearly unstable crack front corrugations might emerge above a critical front propagation speed. We calculate this speed as a function of Poisson's ratio and show that corrugations propagate along the crack front at nearly the Rayleigh wave-speed. Finally, we hypothesize about a possible relation between such corrugations and the long-standing problem of crack branching.Comment: 5 pages, 2 figures + supplementary informatio

Performance Measure Of Some Subspace-Based Methods For Closed-loop System Identification.

This paper presents some of the methods under subspace-based family to perform closed-loop system identification. Three methods have been observed; those are the ORT method, MOESP method and CCA method