Calculation of an optimized telescope apodizer for Terrestrial Planet Finder coronagraphic telescope

One of two approaches to implementing NASA's Terrestrial Planet Finder is to build a space telescope that utilizes the techniques of coronagraphy and apodization to suppress diffraction and image exo-planets. We present a method for calculation of a telescope's apodizer which suppresses the side lobes of the image of a star so as to optimally detect an Earth-like planet. Given the shape of a telescope's aperture and given a search region for a detector, we solve an integral equation to determine an amplitude modulation (an apodizer) which suppresses the star's energy in the focal plane search region. The method is quite general and yields as special cases the product apodizer reported by Nisenson and Papaliolios (2001) and the Prolate spheroidal apodizer of Kasdin et al (2002), and Aime et al (2002). We show computer simulations of the apodizers and the corresponding point spread functions for various aperture-detector configurations.Comment: 16 Pages, 9 figures, Accepted for publication in June issue of PAS

On the Moat-Penumbra Relation

Proper motions in a sunspot group with a delta-configuration and close to the solar disc center have been studied by employing local correlation tracking techniques. The analysis is based on more than one hour time series of G-band images. Radial outflows with a mean speed of 0.67 km s^{-1} have been detected around the spots, the well-known sunspots moats. However, these outflows are not found in those umbral core sides without penumbra. Moreover, moat flows are only found in those sides of penumbrae located in the direction marked by the penumbral filaments. Penumbral sides perpendicular to them show no moat flow. These results strongly suggest a relation between the moat flow and the well-known, filament aligned, Evershed flow. The standard picture of a moat flow originated from a blocking of the upward propagation of heat is commented in some detail.Comment: 4 pages, 4 figures, To appear in ApJ Letter

Looking for CP Violation in W Production and Decay

We describe CP violating observables in resonant $W^\pm$ and $W^\pm$ plus one jet production at the Tevatron. We present simple examples of CP violating effective operators, consistent with the symmetries of the Standard Model, which would give rise to these observables. We find that CP violating effects coming from new physics at the $TeV$ scale could in principle be observable at the Tevatron with $10^6$ $W^\pm$ decays.Comment: 15 pgs with standard LATEX, 7 ps figures embedded with eps

Komunikasi Antarbudaya Di Kalangan Mahasiswa Etnik Papua Dan Etnik Manado Di Universitas Sam Ratulangi Manado

Masyarakat Indonesia tergolong dalam masyarakat heterogen karena terdiri dari berbagai keberagaman suku bangsa, agama, bahasa, adat istiadat dan sebagainya. Dalam melakukan komunikasi untuk memenuhi kebutuhan hidupnya individu ataupun kelompok melakukan interaksi baik sesama etnik maupun dengan individu atau kelompok lain yang berbeda latar belakang budaya, maka di situlah tercipta komunikasi antarbudaya. Komunikasi antarbudaya merupakan komunikasi antar orang-orang yang berbeda budaya (baik dalam arti ras, etnik ataupun perbedaan sosio ekonomi).Dari uraian tersebut, maka penelitian ini bertujuan untuk mengetahui pesan komunikasi verbal dan hambatan-hambatan yang di temui dalam komunikasi antarbudaya di kalangan mahasiswa etnik Papua dan etnik Manado di Fakultas Ilmu Sosial dan Politik, Universitas Sam Ratulangi Manado.Penelitian ini dilakukan di Fakultas Ilmu Sosial dan Politik (FISPOL), Universitas Sam Ratulangi Manado. Metode yang digunakan dalam penelitian ini adalah metode kualitatif dengan teknik pengumpulan data melalui wawancara, observasi/pengamatan, dan dokumentasi. Adapaun informan adalah mahasiswa FISPOL etnik Papua yang berkuliah selama 1 sampai dengan 4 tahun dan mahasiswa FISPOL etnik Manado yakni: Minahasa, Gorontalo, Sangihe Talaud dan Bolmong yang telah menetap di Provinsi Sulawesi Utara sejak kecil. sedangkan tenik analisis data penulis berupaya dengan jalan bekerja dengan data, mengorganisasikan data, memilah-milahnya menjadi satuan yang dapat dikelola, mensistensikannya, mencari dan menemukan pola dan menemukan apa yang penting dari apa yang dipelajari dan memutuskan apa yang dapa di ceritakan kepada orang lain.Hasil penelitian menunjukan bahwa komunikasi antarbudaya di kalangan mahasiswa antara etnik Papua dan etnik Manado di fakultas ilmu sosial dan politik (FISPOL) Universitas Sam Ratulangai Manado berjalan cukup baik dapat dilihat dengan mereka masing-masing menyadari perbedaan yang terjadi namun perbedaan tidak menjadi suatu penghalang untuk mereka terus melakukan interaksi karena kedua etnik ini selalu mengedepankan sikap saling menghargai perbedaan baik dari segi budaya berupa bahasa dan dialek, gaya hidup dan perilaku. Akan tetapi berdasarkan hasil penelitian juga menyatakan bahwa makna dalam komunikasi antarbudaya di kalangan mahasiswa antara etnik Papua dan etnik Manado baik melalui komunikasi secara langsung maupun melalui media sosial (facebook, line, dan BBM) belum berjalan secara optimal karena masing-masing etnik masih menggunakan bahasa dan dialek daerah asal dalam melakukan interaksi sehingga masing-masing individu memiliki persepsi yang berbeda dalam menangkap pesan

Phase diversity restoration of sunspot images I. Relations between penumbral and photospheric features

We investigate the dynamics of and the relations between small-scale penumbral and photospheric features near the outer penumbral boundary: penumbral grains (PGs), dark penumbral fibrils, granules, and photospheric G-band bright points. The analysis is based on a 2 h time sequence of a sunspot close to disc center, taken simultaneously in the G-band and in the blue continuum at 450.7 nm. Observations were performed at the Swedish Vacuum Solar Telescope (La Palma) in July 1999. A total of 2564 images (46 arcsec x 75 arcsec) were corrected for telescope aberrations and turbulence perturbations by applying the inversion method of phase diversity. Our findings can by summarized as follows: (a) One third of the outward-moving PGs pass through the outer penumbral boundary and then either continue moving as small bright features or expand and develop into granules. (b) Former PGs and G-band bright points next to the spot reveal a different nature. The latter have not been identified as a continuation of PGs escaping from the penumbra. The G-band bright points are mostly born close to dark penumbral fibrils where the magnetic field is strong, whereas PGs stem from the less-magnetized penumbral component and evolve presumably to non-magnetic granules or small bright features.Comment: Accepted by A&A, 9 pages and 5 figure

Role of the nonperturbative input in QCD resummed Drell-Yan QTQ_T-distributions

We analyze the role of the nonperturbative input in the Collins, Soper, and Sterman (CSS)'s $b$-space QCD resummation formalism for Drell-Yan transverse momentum ($Q_T$) distributions, and investigate the predictive power of the CSS formalism. We find that the predictive power of the CSS formalism has a strong dependence on the collision energy $\sqrt{S}$ in addition to its well-known $Q^2$ dependence, and the $\sqrt{S}$ dependence improves the predictive power at collider energies. We show that a reliable extrapolation from perturbatively resummed $b$-space distributions to the nonperturbative large $b$ region is necessary to ensure the correct $Q_T$ distributions. By adding power corrections to the renormalization group equations in the CSS formalism, we derive a new extrapolation formalism. We demonstrate that at collider energies, the CSS resummation formalism plus our extrapolation has an excellent predictive power for $W$ and $Z$ production at all transverse momenta $Q_T\le Q$. We also show that the $b$-space resummed $Q_T$ distributions provide a good description of Drell-Yan data at fixed target energies.Comment: Latex, 43 pages including 15 figures; typos were correcte

Exponentiation of the Drell-Yan cross section near partonic threshold in the DIS and MSbar schemes

It has been observed that in the DIS scheme the refactorization of the Drell-Yan cross section leading to exponentiation of threshold logarithms can also be used to organize a class of constant terms, most of which arise from the ratio of the timelike Sudakov form factor to its spacelike counterpart. We extend this exponentiation to include all constant terms, and demonstrate how a similar organization may be achieved in the MSbar scheme. We study the relevance of these exponentiations in a two-loop analysis.Comment: 20 pages, JHEP style, no figure

Massive Lepton Pairs as a Prompt Photon Surrogate

We discuss the transverse momentum distribution for the production of massive lepton-pairs in hadron reactions at fixed target and collider energies within the context of next-to-leading order perturbative quantum chromodynamics. For values of the transverse momentum $Q_T$ greater than the pair mass $Q$, $Q_T > Q$, we show that the differential cross section is dominated by subprocesses initiated by incident gluons. Massive lepton-pair differential cross sections are an advantageous source of constraints on the gluon density, free from the experimental and theoretical complications of photon isolation that beset studies of prompt photon production. We compare calculations with data and provide predictions for the differential cross section as a function of $Q_T$ in proton-antiproton reactions at center-of-mass energies of 1.8 TeV, and in proton-nucleon reactions at fixed target and LHC energies.Comment: 36 pages, RevTeX, including 16 ps files of figures; minor changes in wording; one reference added. Version to appear in Phys Rev