317 research outputs found

    PENGEMBANGAN PROGRAM PENGAJARAN BAHASA INDONESIA SEBAGAI BAHASA ASING PADA JURUSAN PENDIDIKAN BAHASA DAN SASTRA INDONESIA, FAKULTAS BAHASA DAN SENI UNIVERSITAS NEGERI YOGYAKARTA

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    Tujuan jangka panjang dari penelitian ini adalah melakukan pengembangan desain instruksional bagi a) Paket Program PBIPA bagi calon guru Bahasa Indonesia sebagai Bahasa Asing dan b) Paket Program Pengajaran BIPA dan membina jejaring dengan rekanan dalam dan luar negeri yang berminat terhadap pengembangan pengajaran bahasa dan budaya Indonesia. Target khusus yang akan dicapai dikaitkan dengan Kurikulum FBS UNY 2002, bahwa (1) Paket Program PBIPA merupakan paket pilihan yang berdiri sendiri dan kelulusannya diberikan sertifikat terpisah dari transkrip program S1 dan akan dibuka untuk mahasiswa Jurusan Bahasa Indonesia atau non-bahasa Indonesia. Karenanya, perlu dilakukan studi: i) desain instruksional dan beberapa aspeknya, ii) sosialisasi paket pada mahasiswa dan rekanan yang memerlukan lulusan program Paket Pengajaran PBIA, dan iii) melakukan penelitian perbaikan pengajaran untuk semua mata kuliah dalam Paket Pengajaran PBIA; (2) Paket Pengajaran BIPA akan ditekankan pada: i) penyusunan kurikulum bagi program in country 3 atau 6 bulan, pengajaran BIPA bagi keperluan khusus (Indonesian for Specific Purposes), dan penyusunan modul pembelajaran; ii) pembentukan jejaring dan kerjasama dengan universitas di luar negeri yang berminat terhadap pembelajaran bahasa dan budaya Indonesia, dan iii) membina kolaborasi dengan rekanan yang dimungkinkan terlibat dalam pelaksanaan Paket Pengajaran BIPA. Metode yang dipakai disesuaikan dengan tujuan pengembangan, antara lain: survei, observasional, dan berbagai metode yang dipakai dalam research-based teaching. Hasil penelitian ialah sebagai berikut. Dalam rancangan kurikulum 2007, program PBIPA diintegralkan dengan jumlah 144 sks. Hal ini berbeda dengan rancangan semula, yaitu memisahkan program PBIPA dari jumlah 144 sks. Pengintegralan ini sejalan dengan salah satu program I-MHERE, yaitu perintisan Jurusan PBSI menjadi program studi yang bertaraf internasional. Salah satunya ialah dengan memasuk-kan program PBIPA dalam kurikulum 2007 sebagai bagian yang integral dari jumlah 144 sks. Oleh karena hal tersebut, program ini untuk sementara waktu belum dapat dibuka untuk jurusan non PBSI. Silabus telah direvisi berdasarkan angket dan wawancara yang ditujukan kepada pihak-pihak (dosen) yang terlibat BIPA. Berdasarkan silabus yang telah direvisi ini dibuat tujuh modul yang akan diujicobakan pada tahap selanjutnya. Sosialisasi program PBIPA telah dilakukan secara nonformal kepada mahasiswa. Sosialisasi program ini secara formal baru akan dilakukan setelah kurikulum 2007 selesai dibuat. FBS, 2007 (PEND. BHS & SASTRA INDONESIA

    3C454.3 reveals the structure and physics of its 'blazar zone'

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    Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the 'blazar zone', its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinity of the millimeter-photosphere, i.e. at distances where, due to the lateral expansion, the jet becomes transparent at millimeter wavelengths. We conclude that this region is located at ~10 parsecs, the distance coinciding with the location of the hot dust region. This location is consistent with the high amplitude variations observed on ~10 day time scale, provided the Lorentz factor of a jet is ~20. We argue that dissipation is driven by reconfinement shock and demonstrate that X-rays and gamma-rays are likely to be produced via inverse Compton scattering of near/mid IR photons emitted by the hot dust. We also infer that the largest gamma-to-synchrotron luminosity ratio ever recorded in this object - having taken place during its lowest luminosity states - can be simply due to weaker magnetic fields carried by a less powerful jet.Comment: 19 pages, 3 figures, accepted for publication in Ap

    Kink instabilities in jets from rotating magnetic fields

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    We have performed 2.5D and 3D simulations of conical jets driven by the rotation of an ordered, large-scale magnetic field in a stratified atmosphere. The simulations cover about three orders of magnitude in distance to capture the centrifugal acceleration as well as the evolution past the Alfven surface. We find that the jets develop kink instabilities, the characteristics of which depend on the velocity profile imposed at the base of the flow. The instabilities are especially pronounced with a rigid rotation profile, which induces a shearless magnetic field. The jet's expansion appears to be limiting the growth of Alfven mode instabilities.Comment: 10 pages, 13 figures, accepted for publication in A&

    Structure and Stability of Keplerian MHD Jets

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    MHD jet equilibria that depend on source properties are obtained using a simplified model for stationary, axisymmetric and rotating magnetized outflows. The present rotation laws are more complex than previously considered and include a Keplerian disc. The ensuing jets have a dense, current-carrying central core surrounded by an outer collar with a return current. The intermediate part of the jet is almost current-free and is magnetically dominated. Most of the momentum is located around the axis in the dense core and this region is likely to dominate the dynamics of the jet. We address the linear stability and the non-linear development of instabilities for our models using both analytical and 2.5-D numerical simulation's. The instabilities seen in the simulations develop with a wavelength and growth time that are well matched by the stability analysis. The modes explored in this work may provide a natural explanation for knots observed in astrophysical jets.Comment: 35 pages, accepted by the Ap

    Cosine and Sine Operators Related with Orthogonal Polynomial Sets on the Intervall [-1,1]

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    The quantization of phase is still an open problem. In the approach of Susskind and Glogower so called cosine and sine operators play a fundamental role. Their eigenstates in the Fock representation are related with the Chebyshev polynomials of the second kind. Here we introduce more general cosine and sine operators whose eigenfunctions in the Fock basis are related in a similar way with arbitrary orthogonal polynomial sets on the intervall [-1,1]. To each polynomial set defined in terms of a weight function there corresponds a pair of cosine and sine operators. Depending on the symmetry of the weight function we distinguish generalized or extended operators. Their eigenstates are used to define cosine and sine representations and probability distributions. We consider also the inverse arccosine and arcsine operators and use their eigenstates to define cosine-phase and sine-phase distributions, respectively. Specific, numerical and graphical results are given for the classical orthogonal polynomials and for particular Fock and coherent states.Comment: 1 tex-file (24 pages), 11 figure

    Physical properties of the jet in 0836+710 revealed by its transversal structure

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    Studying the internal structure of extragalactic jets is crucial for understanding their physics. The Japanese-led space VLBI project VSOP has presented an opportunity for such studies, by reaching baseline lengths of up to 36,000 km and resolving structures down to an angular size of 0.3\approx 0.3 mas at 5 GHz. VSOP observations of the jet in 0836+710 at 1.6 and 5 GHz have enabled tracing of the radial structure of the flow on scales from 2 mas to 200 mas along the jet and determination of the wavelengths of individual oscillatory modes responsible for the formation of the structure observed. We apply linear stability analysis to identify the oscillatory modes with modes of Kelvin-Helmholtz instability that match the wavelengths of the structures observed. We find that the jet structure in 0836+710 can be reproduced by the helical surface mode and a combination of the helical and elliptic body modes of Kelvin-Helmholtz instability. Our results indicate that the jet is substantially stratified and different modes of the instability grow inside the jet at different distances to the jet axis. The helical surface mode can be driven externally, and we discuss the implications of the driving frequency on the physics of the active nucleus in 0836+710.Comment: Accepted for publication in Astronomy & Astrophysics Letter

    Bendings of radio jets in BL Lacertae objects I: EVN and MERLIN observations

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    Several blazars, and BL Lac objects in particular, show a misalignment between the jet orientation on parsec and kiloparsec scales. Some authors (i.e. Conway & Murphy, 1993) have attempted to explain this behaviour invoking helical jets for misalignment angles around 90\degr, showing how in this case there are interesting implications for the understanding of the medium into which the jet is expanding. By comparing sensitive VLA observations (Cassaro et al., 1999) with images available in the literature for the BL Lac objects from the 1-Jy Sample (Stickel et al., 1991), it is clear that there is a wide range of misalignments between the initial jet direction and the kpc-scale jet, when detected. We have carried out VLBI observations of these BL Lac objects, in order to investigate the spatial evolution of the radio jets from few tens to hundreds of mas, and to search for helical jets in this class of sources. We present here the first dataset obtained from EVN+MERLIN observations at 5 GHz for seven objects. From these observations we never have a clear detection of helical jets, we only have a possible signature of their presence in 2 objects. In only one of the sources with a misalignment angle around 90\degr the presence of helical jets can be ruled out. This implies that it is not possible to invoke helical jets to explain the morphology of all the sources showing a misalignment of about 90\degr between the parsec and the kiloparsec scale jets.Comment: 12 pages, 9 figures, latex, accepted by Astronomy & Astrophysic

    A Sample of Low Redshift BL Lacs. I. The Radio Data

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    We present a new sample of 30 nearby (z<0.2) BL Lacs, selected to study the nuclear as well as the large scale properties of low power radio sources. In this first paper, we show and discuss new radio data taken with the VLA (19 objects at 1.4 GHz, either in A or C configuration, or both) as well as with the VLBA (15 sources at 5 GHz). On the kiloparsec scale, all objects exhibit a compact core and a variety of radio morphologies (jets, halos, secondary compact components). On the parsec scale, we find weak cores and a few short, one-sided, jets. From the jet/counter-jet ratio, core dominance, and synchrotron self Compton model we estimate the intrinsic orientation and velocity of the jets. The resulting properties of BL Lacs are similar to those of a parent population composed of FR I radio galaxies.Comment: 46 pages, 12 figures, accepted for publication in Ap

    Imaging nonequilibrium atomic vibrations with x-ray diffuse scattering

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    For over a century, x-ray scattering has been the most powerful tool for determining the equilibrium structure of crystalline materials. Deviations from perfect periodicity, for example due to thermal motion of the atoms, reduces the intensity of the Bragg peaks as well as produces structure in the diffuse scattering background. Analysis of the thermal diffuse scattering (TDS) had been used to determine interatomic force constants and phonon dispersion in relatively simple cases before inelastic neutron scattering became the preferred technique to study lattice dynamics. With the advent of intense synchrotron x-ray sources, there was a renewed interest in TDS for measuring phonon dispersion. The relatively short x-ray pulses emanating from these sources also enables the measurement of phonon dynamics in the time domain. Prior experiments on nonequilibrium phonons were either limited by time-resolution and/or to relatively long wavelength excitations. Here we present the first images of nonequilibrium phonons throughout the Brillouin zone in photoexcited III-V semiconductors, indium-phosphide and indium-antimonide, using picosecond time-resolved diffuse scattering. In each case, we find that the lattice remain out of equilibrium for several hundred picoseconds up to nanoseconds after laser excitation. The non-equilibrium population is dominated by transverse acoustic phonons which in InP are directed along high-symmetry directions. The results have wide implications for the detailed study of electron-phonon and phonon-phonon coupling in solids.Comment: 10 pages, 3 figure

    Waves and Instabilities in Accretion Disks: MHD Spectroscopic Analysis

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    A complete analytical and numerical treatment of all magnetohydrodynamic waves and instabilities for radially stratified, magnetized accretion disks is presented. The instabilities are a possible source of anomalous transport. While recovering results on known hydrodynamicand both weak- and strong-field magnetohydrodynamic perturbations, the full magnetohydrodynamic spectra for a realistic accretion disk model demonstrates a much richer variety of instabilities accessible to the plasma than previously realized. We show that both weakly and strongly magnetized accretion disks are prone to strong non-axisymmetric instabilities.The ability to characterize all waves arising in accretion disks holds great promise for magnetohydrodynamic spectroscopic analysis.Comment: FOM-Institute for plasma physics "Rijnhuizen", Nieuwegein, the Netherlands 12 pages, 3 figures, Accepted for publication in ApJ
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