The Stellar Dynamics of Omega Centauri

The stellar dynamics of Omega Centauri are inferred from the radial velocities of 469 stars measured with CORAVEL (Mayor et al. 1997). Rather than fit the data to a family of models, we generate estimates of all dynamical functions nonparametrically, by direct operation on the data. The cluster is assumed to be oblate and edge-on but mass is not assumed to follow light. The mean motions are consistent with axisymmetry but the rotation is not cylindrical. The peak rotational velocity is 7.9 km/s at 11 pc from the center. The apparent rotation of Omega Centauri is attributable in part to its proper motion. We reconstruct the stellar velocity ellipsoid as a function of position, assuming isotropy in the meridional plane. We find no significant evidence for a difference between the velocity dispersions parallel and perpendicular to the meridional plane. The mass distribution inferred from the kinematics is slightly more extended than, though not strongly inconsistent with, the luminosity distribution. We also derive the two-integral distribution function f(E,Lz) implied by the velocity data.Comment: 25 Latex pages, 12 Postscript figures, uses aastex, epsf.sty. Submitted to The Astronomical Journal, December 199

The dynamical structure factor in disordered systems

We study the spectral width as a function of the external momentum for the dynamical structure factor of a disordered harmonic solid, considered as a toy model for supercooled liquids and glasses. Both in the context of single-link coherent potential approximation and of a single-defect approximation, two different regimes are clearly identified: if the density of states at zero energy is zero, the Rayleigh $p^4$ law is recovered for small momentum. On the contrary, if the disorder induces a non vanishing density of states at zero energy, a linear behaviour is obtained. The dynamical structure factor is numerically calculated in lattices as large as $96^3$, and satisfactorily agrees with the analytical computations.Comment: 7 pages plus 4 postscript figure

Conformal and gauge invariant spin-2 field equations

Using an approach based on the Casimir operators of the de Sitter group, the conformal invariant equations for a fundamental spin-2 field are obtained, and their consistency discussed. It is shown that, only when the spin-2 field is interpreted as a 1-form assuming values in the Lie algebra of the translation group, rather than a symmetric second-rank tensor, the field equation is both conformal and gauge invariant.Comment: 12 pages, no figures; accepted for publication in Gravitation & Cosmolog

Abundance ratios of volatile vs. refractory elements in planet-harbouring stars: hints of pollution?

We present the [X/H] trends as function of the elemental condensation temperature Tc in 88 planet host stars and in a volume-limited comparison sample of 33 dwarfs without detected planetary companions. We gathered homogeneous abundance results for many volatile and refractory elements spanning a wide range of Tc, from a few dozens to several hundreds kelvin. We investigate possible anomalous trends of planet hosts with respect to comparison sample stars in order to detect evidence of possible pollution events. No significant differences are found in the behaviour of stars with and without planets. This result is in agreement with a ``primordial'' origin of the metal excess in planet host stars. However, a subgroup of 5 planet host and 1 comparison sample stars stands out for having particularly high [X/H] vs. Tc slopes.Comment: 10 pages, 7 figures, accepted for publication in A&A. Figures with higher resolution are available at www.iac.es/proyect/abuntes

Vibrations in glasses and Euclidean Random Matrix theory

We study numerically and analytically a simple off-lattice model of scalar harmonic vibrations by means of Euclidean random matrix theory. Since the spectrum of this model shares the most puzzling spectral features with the high-frequency domain of glasses (non-Rayleigh broadening of the Brillouin peak, boson peak and secondary peak), the Euclidean random matrix theory provide a single and fairly simple theoretical framework to their explanation.Comment: 11 pages, 7 postscript figures, Proceedings of Statphys 2

Vibrational spectra in glasses

The findings of X-ray and neutron scattering experiments on amorphous systems are interpreted within the framework of the theory of Euclidean random matrices. This allows to take into account the topological nature of the disorder, a key ingredient which strongly affects the vibrational spectra of those systems. We present a resummation scheme for a perturbative expansion in the inverse particle density, allowing an accurate analytical computation of the dynamical structure factor within the range of densities encountered in real systems.Comment: Talk given at the '8th International Workshop on Disordered Systems' Andalo, Trento, 12-15 March 200

Delik Aduan Terhadap Perkara Kekerasan Seksual Dalam Rumah Tangga

Negara berpandangan bahwa segala bentuk kekerasan, terutama kekerasan dalam rumah tangga, adalah pelanggaran hak asasi manusia dan kejahatan terhadap martabat kemanusiaan serta bentuk diskriminasi. Perkembangan dewasa ini menunjukkan bahwa tindak kekerasan secara fisik, psikis, seksual, dan penelantaran rumah tangga pada Kenyataannya terjadi sehingga dibutuhkan perangkat hukum yang memadai untuk menghapus kekerasan dalam rumah tangga. Secara umum di dalam Kitab Undang-Undang Hukum Pidana telah diatur mengenai penganiayaan dan kesusilaan serta penelantaran orang yang perlu diberikan nafkah dan kehidupan.Dari latar belakang di atas, maka yang menjadi permasalahan dalam karya tulis ini yaitu bagaimana terjadinya kekerasan seksual dalam rumah tangga dan bagaimana delik aduan terhadap perkara kekerasan seksual dalam rumah tangga. Karya tulis ini menggunakan metode penelitian yuridis normatif dan melalui metode ini dapat ditelaah peraturan Perundang-undangan yang mengatur mengenai delik aduan dalam perkara kekerasan seksual dalam rumah tangga serta teori-teori dari ahli hukum yang ada dalam literatur-literatur dan karya-karya ilmiah hukum dan untuk menjelaskan beberapa istilah dan pengertian, maka digunakan kamus-kamus hukum. Untuk mengumpulkan bahan-bahan hukum yang diperlukan, penulis melakukan studi kepustakaan. Hasil penelitian menunjukkan bahwa tindakan kekerasan merupakan wujud penindasan dan pelanggaran hak asasi yang dilakukan seseorang kepada orang lain, kelompok tertentu kepada kelompok lain, orang dewasa, anak-anak, majikan kepada pembantunya dan laki-laki kepada perempuan. Hubungan seksual yang dipaksakan merupakan bentuk kekerasan yang mengakibatkan kerugian bagi korban.Undang-Undang Republik Indonesia Nomor 23 Tahun 2004 Tentang Penghapusan Kekerasan Dalam Rumah Tangga. Pasal 51: Tindak pidana kekerasan fisik sebagaimana dimaksud dalam Pasal 44 ayat (4) merupakan delik aduan.Setiap orang yang melakukan perbuatan kekerasan seksual dipidana dengan pidana penjara paling lama 12 (dua belas) tahun atau denda paling banyak Rp36.000.000,00 (tiga puluh enam juta rupiah).Delik aduan merupakan kejahatan yang dapat dituntut apabila ada pengaduan dari pihak yang menjadi korban kekerasan seksual yang dirugikan. Dari hasil penelitian dapat ditarik kesimpulan bahwa terjadinya kekerasan seksual dalam rumah tangga akibat adanya pemaksaan hubungan seksual yang dilakukan terhadap orang yang menetap dalam lingkup rumah tangga tersebut dan pemaksaan hubungan seksual terhadap salah seorang dalam lingkup rumah tangganya dengan orang lain untuk tujuan komersial dan/atau tujuan tertentu. Delik aduan terhadap kekerasan seksual dalam rumah tangga, baik yang dilakukan oleh suami terhadap isteri atau sebalikny

Temperature chaos in 3D Ising Spin Glasses is driven by rare events

Temperature chaos has often been reported in literature as a rare-event driven phenomenon. However, this fact has always been ignored in the data analysis, thus erasing the signal of the chaotic behavior (still rare in the sizes achieved) and leading to an overall picture of a weak and gradual phenomenon. On the contrary, our analysis relies on a large-deviations functional that allows to discuss the size dependencies. In addition, we had at our disposal unprecedentedly large configurations equilibrated at low temperatures, thanks to the Janus computer. According to our results, when temperature chaos occurs its effects are strong and can be felt even at short distances.Comment: 5 pages, 5 figure