Spherically symmetric inhomogeneous dust collapse in higher dimensional space-time and cosmic censorship hypothesis

We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.     

Scattering by small defects in the neighbourhood of a fluid-solid interface

The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions.     

The structure of the space of solutions of Einstein’s equations coupled with scalar fields

Following the work of Arms, Fischer, Marsden and Moncrief, it is proved that the space of solutions of Einstein’s equations coupled with self-gravitating mass-less scalar fields has conical singularities at each spacetime possessing a compact Cauchy surface of constant mean curvature and a nontrivial set of simultaneous Killing fields, either all spacelike or including one (independent) timelike.     

On a Simple Nonisothermal Adsorption Experiment with Organic Vapors and an Inertial Microbalance To Study the Surface Properties of Hybrid (Organic/Inorganic) Porous Materials

A nonisothermal adsorption experiment using a controlled flow of cyclopentane in the 333-313 K range is used to simultaneously estimate the specific surface area and micropore volume of a hybrid (organic/inorganic) alcogel. For reference, the method is also applied to an all-inorganic material with a more rigid structure, namely, a high surface area SiO(2)-Al(2)O(3). The proposed data analysis provides guidelines to determine whether adsorption data on a certain adsorbate/adsorbent system can be modeled effectively as a convolution of BET (meso- and macropore) and Dubinin-Radushkevitch (DR, micropore) contributions. Copyright 2000 Academic Press.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.     

Genericity and stability of naked singularities arising in an inhomogeneous dust collapse

In this paper, we consider an inhomogeneous dust collapse, and extend earlier works of Jhingan, Joshi, and Singh to the case where initial density and velocity distributions are finitely differentiable functions of co-moving coordinate r. We study the occurrence of naked singularities under various conditions on the derivatives of initial density and velocity distributions in marginally as well as non-marginally bound case. We then study their stability and genericity with respect to perturbations in the initial data in an appropriate topological sense.     

Linearization stability of coupled gravitational and scalar fields in asymptotically flat space-times

Using the methods of Choquet-Bruhat, Fischer and Marsden and using weighted Sobolev spaces developed recently by Christodoulou and Choquet-Bruhat, it is proved that the Einstein field equations coupled with self-gravitating scalar fields are linearization stable in asymptotically flat space-times.     

Meson production in p + d reactions

Total and differential cross sections for the reactions p + d → ³He + m ⁰ with m=π, η and p + d → ³H+π⁺ were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward-backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied. Representing the GEM Collaboration     

Interaction between explosive and analyte layers in explosive matrix-assisted plasma desorption mass spectrometry

An HMX/insulin two-layer system was chosen as a model for further investigation of the matrix properties of explosive materials for protein analytes in plasma desorption mass spectrometry. The dependencies of the molecular ion yield and average charge state as a function of the analyte thickness were studied. An increase in the charge state of multiply protonated molecular species was confirmed as the major matrix effect, with the average charge state z at the smallest thickness studied being higher than in matrix-assisted laser desorption/ionization and closer to the value obtained in electrospray ionization under standard acidic conditions. Observed charge state distributions are significantly narrower than the corresponding Poisson distributions, which suggests that the protonation of insulin is limited in plasma desorption by the number of basic sites in the molecule, similar to electrospray ionization. Both the curve displaying total molecular ion yield and the one showing the total charge (proton) yield as a function of the insulin thickness have maxima at a thickness different from an insulin monolayer. These observations diminish the significance of a matrix/analyte interface mechanism for the explosive matrix assistance. Instead, a mechanism related to the chemical energy release during conversion of the explosive after the ion impact is proposed. As additional mechanisms, enhanced protonation of the analyte through collisions with products of the explosive decay is considered, as well as electron scavenging by other products, which leads to a higher survival probability of positively charged protein molecular ions. Copyright 1999 John Wiley & Sons, Ltd.     

Stability of naked singularity arising in gravitational collapse of Type I matter fields

Considering gravitational collapse of Type I matter fields, we prove that, given an arbitrary C²-mass functionM(r, v) and a C¹-functionh(r, v) (through the corresponding C¹-metric functionν(t, r)), there exist infinitely many choices of energy distribution functionb(r) such that the ’true’ initial data(M, h(r,v)) leads the collapse to the formation of naked singularity. We further prove that the occurrence of such a naked singularity is stable with respect to small changes in the initial data. We remark that though the initial data leading to both black hole (BH) and naked singularity (NS) form a ’big’ subset of the true initial data set, their occurrence is not generic. The terms ’stability’ and ’genericity’ are appropriately defined following the theory of dynamical systems. The particular case of radial pressurep _r (r) has been illustrated in details to get a clear picture of how naked singularity is formed and how, it is stable with respect to initial data.