The electromagnetic ram action of the plasma focus as a paradigm for the generation of cosmic rays and the gigantic jets in active galaxies

Recent measurements of the energy spectrum of the plasma-focus-generated deuteron beam yield as spectrum of the form N(E)=(approx.) E to the -2.7 for 1MeV E 13 MeV. Other measurements show that the beta 1 electron beam which is generated simultaneously with the deuteron beam is interrupted into segments of spacing 25ps and duration approximately 4ps. A stuttering-electro-magnetic-ram (ser) model of the plasma focus in proposed which is similar to Raudorf's electronic ram which produces a similar spectrum for an electron beam for 1Mev E 10MeV. It is proposed that the cosmic ray spectrum and the giganic galactic jets are both generated by ser action near the centers of active galaxies

A Quantitative Analysis of Charmonium Suppression in Nuclear Collisions

Data from J/psi and psi' production in p-A collisions are used to determine the cross section for absorption of pre-resonance charmonium in nuclear matter. The J/psi suppression in O-Cu, O-U and S-U collisions is fully reproduced by the corresponding nuclear absorption, while Pb-Pb collisions show an additional suppression increasing with centrality. We study the onset of this change in terms of hadronic comover interactions and conclude that so far no conventional hadronic description can consistently account for all data. Deconfinement, starting at a critical point determined by central S-U collisions, is in accord with the observed suppression pattern.Comment: 37 pages, 12 figures, uses epsfig style, LaTe

Shear Viscosity of Quark Matter

We consider the shear viscosity of a system of quarks and its ratio to the entropy density above the critical temperature for deconfinement. Both quantities are derived and computed for different modeling of the quark self-energy, also allowing for a temperature dependence of the effective mass and width. The behaviour of the viscosity and the entropy density is argued in terms of the strength of the coupling and of the main characteristics of the quark self-energy. A comparison with existing results is also discussed.Comment: 15 pages, 4 figure

String Clustering and J/Psi Suppression in Nuclear Collisions

We study the clustering of colour strings in the transverse plane of nucleus-nucleus collisions and argue that deconfinement sets in when the string density within a cluster reaches a critical value. We show that this implies a minimal cluster size at the onset of deconfinement, which in turn results in discontinuous behaviour for J/Psi suppression.Comment: 9 pages, latex, three figures (included

Mesonic correlation functions at finite temperature and density in the Nambu-Jona-Lasinio model with a Polyakov loop

We investigate the properties of scalar and pseudo-scalar mesons at finite temperature and quark chemical potential in the framework of the Nambu-Jona-Lasinio (NJL) model coupled to the Polyakov loop (PNJL model) with the aim of taking into account features of both chiral symmetry breaking and deconfinement. The mesonic correlators are obtained by solving the Schwinger-Dyson equation in the RPA approximation with the Hartree (mean field) quark propagator at finite temperature and density. In the phase of broken chiral symmetry a narrower width for the sigma meson is obtained with respect to the NJL case; on the other hand, the pion still behaves as a Goldstone boson. When chiral symmetry is restored, the pion and sigma spectral functions tend to merge. The Mott temperature for the pion is also computed.Comment: 24 pages, 9 figures, version to appear in Phys. Rev.

Delay performance in random-access grid networks

We examine the impact of torpid mixing and meta-stability issues on the delay performance in wireless random-access networks. Focusing on regular meshes as prototypical scenarios, we show that the mean delays in an $L\times L$ toric grid with normalized load $\rho$ are of the order $(\frac{1}{1-\rho})^L$. This superlinear delay scaling is to be contrasted with the usual linear growth of the order $\frac{1}{1-\rho}$ in conventional queueing networks. The intuitive explanation for the poor delay characteristics is that (i) high load requires a high activity factor, (ii) a high activity factor implies extremely slow transitions between dominant activity states, and (iii) slow transitions cause starvation and hence excessively long queues and delays. Our proof method combines both renewal and conductance arguments. A critical ingredient in quantifying the long transition times is the derivation of the communication height of the uniformized Markov chain associated with the activity process. We also discuss connections with Glauber dynamics, conductance and mixing times. Our proof framework can be applied to other topologies as well, and is also relevant for the hard-core model in statistical physics and the sampling from independent sets using single-site update Markov chains

Kaon and Φ\Phi production vs Participants in Nuclear Collisions

Data on kaon and $\Phi$ production in nuclear collisions as a function of centrality are analysed both at AGS and SPS energy range. We compare the results of several experiments, looking for common trend in `participant scaling' of production yields. We find a smooth description of scaled kaon and $\Phi$ yields as a function of participant density. We also show a participant density dependence of kaons and $\Phi$ produced in the forward hemisphere for proton-nucleus collisions.Comment: Proceedings of the International Conference on Strangeness in Quark Matter, 20-25 July 2000, Berkeley, CA. To appear in Journal of Physics G: Nuclear and Particle Physic

Peningkatan Motivasi Belajar Matematika Melalui Pendekatan Contextual Teaching And Learning Bagi Siswa Kelas X Semester I SMA Islam Sudirman 2 Boyolali Tahun Ajaran 2011/2012

Penelitian ini bertujuan mengkaji dan mendiskripsikan peningkatan motivasi belajar matematika siswa melalui pendekatan pembelajaran kontekstual. Pendekatan penelitian adalah penelitian kualitatif dengan desain Penelitian Tindakan Kelas (PTK). Subyek penelitian yang dikenai tindakan adalah siswa kelas x Sma Islam Sudirman 2 Boyolali, yang berjumlah 27 siswa. Metode pengumpulan data, observasi, catatan lapangan, dan dokumentasi. Teknik analisis data secara deskriptif kualitatif dengan metode alur. Keabsahan data dilakukan dengan observasi secara terus menerus dan triangulasi data. Hasil penelitian ini menunjukkan adanya peningkatan motivasi belajar siswa yang dapat dilihat dari meningkatnya indikator banyaknya siswa yang antusias dalam: a) persiapan dalam mengikuti pembelajaran, sebelum tindakan 33,33%, putaran I 48,14%, putaran II 66,66%,dan pada putaran III 77,77% b) belajar kelompok sebelum tindakan 25,92%, putaran I 37,03%, putaran II 62,96% , dan pada putaran III 74,07%.c) menanggapi atau mengajukan pertanyaan, sebelum tindakan 7,40%, putaran I 14,81%, putaran II 33,33%, dan pada putaran III 48,14%. Kesimpulan penelitian ini adalah bahwa penerapan strategi pembelajaran kontekstual dapat meningkatkan motivasi belajar sisw

Anomalous J/Psi suppression and the nature of deconfinement

We study the characteristic features of J/Psi suppression by deconfinement. A first order phase transition leads to an essentially discontinuous onset of anomalous J/Psi suppression. The different energy densities required for the dissociation of different charmonium states result in a two-step suppression pattern, in which first the J/Psi's from chi decays are suppressed and subsequently the directly produced J/Psi states. Combining both features leads to a unique form of J/Psi suppression in a deconfining medium.Comment: LaTex, 7 pages, 2 figure

Charge-Reversal Instability in Mixed Bilayer Vesicles

Bilayer vesicles form readily from mixtures of charged and neutral surfactants. When such a mixed vesicle binds an oppositely-charged object, its membrane partially demixes: the adhesion zone recruits more charged surfactants from the rest of the membrane. Given an unlimited supply of adhering objects one might expect the vesicle to remain attractive until it was completely covered. Contrary to this expectation, we show that a vesicle can instead exhibit {\it adhesion saturation,} partitioning spontaneously into an attractive zone with definite area fraction, and a repulsive zone. The latter zone rejects additional incoming objects because counterions on the interior of the vesicle migrate there, effectively reversing the membrane's charge. The effect is strongest at high surface charge densities, low ionic strength, and with thin, impermeable membranes. Adhesion saturation in such a situation has recently been observed experimentally [H. Aranda-Espinoza {\it et al.}, {\sl Science} {\bf285} 394--397 (1999)]