305 research outputs found

    On Superconnections and the Tachyon Effective Action

    Get PDF
    We propose a form of the effective action of the tachyon and gauge fields for brane-antibrane systems and non-BPS Dp-branes, written in terms of the supercurvature. Kink and vortex solutions with constant infinite gauge field strength reproduce the exact tensions of the lower-dimensional D-branes. We discuss the relation to BSFT and other models in the literature

    An AKARI Search for Intracluster Dust of Globular Clusters

    Full text link
    We report the observations of 12 globular clusters with the AKARI/FIS. Our goal is to search for emission from the cold dust within clusters. We detect diffuse emissions toward NGC 6402 and 2808, but the IRAS 100-micron maps show the presence of strong background radiation. They are likely emitted from the galactic cirrus, while we cannot rule out the possible association of a bump of emission with the cluster in the case of NGC 6402. We also detect 28 point-like sources mainly in the WIDE-S images (90 micron). At least several of them are not associated with the clusters but background galaxies based on some external catalogs. We present the SEDs by combining the near-and-mid infrared data obtained with the IRC if possible. The SEDs suggest that most of the point sources are background galaxies. We find one candidate of the intracluster dust which has no mid-infrared counterpart unlike the other point-like sources, although some features such as its point-like appearance should be explained before we conclude its intracluster origin. For most of the other clusters, we have confirmed the lack of the intracluster dust. We evaluate upper limits of the intracluster dust mass to be between 1.0E-05 and 1.0E-03 solar mass depending on the dust temperature. The lifetime of the intracluster dust inferred from the upper limits is shorter than 5 Myr (T=70K) or 50 Myr (35K). Such short lifetime indicates some mechanism(s) are at work to remove the intracluster dust. We also discuss its impact on the chemical evolution of globular clusters.Comment: Accepted for publication in PASJ AKARI special issue. 14 pages, 11 figure

    Pengaruh Kontaminasi Logam Berat di Sedimen terhadap Komunitas Bentik Makroavertebrata: Studi Kasus di Waduk Saguling-Jawa Barat

    Full text link
    Waduk Saguling sekarang ini mengalami beberapa permasalahan yang serius antara lain penurunan kualitas air oleh kontaminasi bahan organik, logam berat, pestisida dan bahan mikropolutan lainnya. Penelitian ini bertujuan untuk melihat besarnya kontaminasi logam berat di sedimen dan dampaknya pada komunitas bentik makroavertebrata. Penarikan contoh telah dilakukan pada bulan Juni hingga September 2004. Hasil penelitian menunjukkan kontaminasi logam Pb dan Cu di sedimen yang paling berpotensi menimbulkan gangguan pada ekosistem perairan, sedangkan logam Cd masih di bawah beberapa guideline kualitas sedimen. Penelitian ini juga mengindikasikan beberapa atribut biologi seperti: indek diversitas, kekayaan taxa, dan Indeks BMWP relatif sensitif untuk mendeteksi gangguan ekologi yang disebabkan oleh peningkatan kontaminasi logam berat di sedimen

    Hubungan Gangguan Masa Menopause dengan Tingkat Kecemasan pada Ibu Menopause di Desa Dawuhan Kecamatan Purwoasri Kabupaten Kediri

    Full text link
    Menopause adalah suatu masa berakhirnya reproduksi wanita yang disebabkan berkurangnya hormon estrogen dan progesteron yang ditandai oleh berhentinya haid. Pada masa ini terjadi gangguan yang menimbulkan kecemasan dan berdampak memacu organ tubuh tidak stabil. Hal ini membuat wanita menopause merasa terganggu dalam menjalankan kegiatan sehari-hari. Penelitian ini bertujuan untuk menganalisa hubungan gangguan masa menopause dengan tingkat kecemasan pada ibu menopause. Penelitian dilaksanakan pada tanggal 22-26 Januari 2014 di Desa Dawuhan Kecamatan Purwoasri Kabupaten Kediri. Desain penelitian menggunakan desain studi korelasional dengan variabel independen gangguan masa menopause pada wanita, variabel dependen tingkat kecemasan wanita saat menopause, dengan populasi wanita menopause 105 jiwa, jumlah sampel adalah 84 responden wanita menopause usia 45-55 tahun diambil secara simple random sampling. Pengumpulan data menggunakan kuesioner berupa skala MRS untuk variabel independen dan TMAS untuk variabel dependen. Analisa data menggunakan uji Chi Square. Hasil analisis dengan Chi Square metode penghitungan manual X2 hitung > X2 tabel yaitu13,75 > 7,815 sehingga H1 terbukti yang artinya hubungan gangguan masa menopause dengan tingkat kecemasan pada ibu menopause di Desa Dawuhan, Kecamatan Purwoasri Kabupaten Kediri. Dalam penghitungan manual koefisien kontingensi didapatkan nilai 0,375 maka hubungan antara kedua variable rendah. Adanya Perubahan fisik wanita menopause menyebabkan kecemasan pada wanita menopause, tetapi ada faktor-faktor lain seperti sikap, gaya hidup, faktor kultur maupun psikologis serta status sosial ekonomi, yang mempengaruhi kecemasan wanita menopause

    SiO Maser Survey of the Large-Amplitude Variables in the Galactic Center

    Full text link
    We have surveyed ~400 known large-amplitude variables within 15' of the galactic center in the SiO J=1--0 v=1 and 2 maser lines at 43 GHz, resulting in 179 detections. SiO lines were also detected from 16 other resulting in 180 detections. SiO lines were also detected from 16 other sources, which are located within 20" (the telescope half beamwidth) of the program objects. The detection rate of 48 percent is comparable to that obtained in Bulge IRAS source surveys. Among the SiO detections, five stars have radial velocities greater than 200 km/s. The SiO detection rate increases steeply with the period of light variation, particularly for stars with P>500 d, where it exceeds 80%. We found that, at a given period, the SiO detection rate is approximately three times that for OH. These facts suggest that the large-amplitude variables in the Nuclear Disk region are AGB stars similar in their overall properties to the inner and outer Bulge IRAS/SiO sources. From the set of radial velocity data, the mass distribution within 30 pc of the galactic center is derived by a new method which is based on the collisionless Boltzmann equation integrated along the line of sight. The mass within 30 pc is about 6.4 [\pm 0.7] \times 10^7 M_{\odot} and the mass of the central black hole is 2.7 [\pm 1.3] \times 10^6 M_{\odot}. Consideration of the line-of-sight velocity of each star and its potential energy leads to the conclusion that the five high-velocity stars come from galactocentric distances as high as 300 pc. The high-velocity subsample of stars with negative radial velocities exhibits a tendency to have brighter K magnitudes than the subsample of stars with positive velocities. The origin of these high-velocity stars is discussed.Comment: Hires. figures are available as No.604 of NRO report at http://www.nro.nao.ac.jp/library/report/list.html . PASJ 56 (april 28 issue) in pres

    Detections of SiO Masers from the Large-Amplitude Variables in the Galactic Nuclear Disk

    Get PDF
    We have surveyed known large-amplitude variables within 15' of the Galactic center in the SiO J=1-0 v=1 and 2 maser lines at 43 GHz, resulting in 79 detections and 58 non-detections. The detection rate of 58 percent is comparable to that obtained in Bulge IRAS source surveys. SiO lines were also detected from four other sources near the program objects. The SiO detection rate increases steeply with the period, particularly for stars with P>500 d, where it exceeds 80%. We found at a given period that the SiO detection rate is approximately double that for OH. These facts suggest that the large-amplitude variables in the Nuclear Disk region are AGB stars similar in their overall properties to the inner and outer bulge IRAS/SiO sources.Comment: 5 pages, 2 figures, 1 Table. PASJ 54, No 2 April 25 issue in pres

    SiO Maser Survey of IRAS Sources in the Inner Galactic Disk

    Full text link
    We have surveyed 401 color selected IRAS sources in the Galactic disk in the SiO J=1--0 v= 1 and 2 maser lines at 43 GHz, resulting in 254 (239 new) detections. The observed sources lie mostly in a strip of the inner Galactic disk with boundaries -10<l<40 deg and |b|<3 deg. This survey provides radial velocities of inner-disk stars for which optical measurements cannot be made due to interstellar extinction. The SiO ll--vv diagram in the area −10<l<40degexhibitsfewerobjectscoincidentwiththemolecularringfeaturethantheOH1612MHzsource-10<l<40 deg exhibits fewer objects coincident with the molecular ring feature than the OH 1612 MHz source l−−--v$ map does, indicating a slight difference of stellar type between SiO and OH emitting stars. After identifying all of the SiO detected sources in the 2MASS near-infrared catalog, we computed their luminosity distances based on the infrared fluxes. We then mapped these objects onto the first quadrant of the Galactic plane. Combining the distances with the SiO radial-velocities, we obtained a pattern speed for SiO maser sources, Omega_P=21 (+- 13) km s^{-1} kpc^{-1}, between the distances 1 and 5.5 kpc, without the use of any dynamical models. The increase of the pattern speed toward the Galactic center (up to 60 km s^{-1} kpc^{-1} between the distances, 5.5 and 7 kpc) suggests the presence of two pattern speeds in the Galaxy.Comment: 38 page 9 figures, high res. eps files are available as NRO report No. 608 (http://www.nro.nao.ac.jp/library/report/list.html). PASJ 56 No. 4 in pres

    Characterization and Improvement of the Image Quality of the Data Taken with the Infrared Camera (IRC) Mid-Infrared Channels onboard AKARI

    Full text link
    Mid-infrared images frequently suffer artifacts and extended point spread functions (PSFs). We investigate the characteristics of the artifacts and the PSFs in images obtained with the Infrared Camera (IRC) onboard AKARI at four mid-infrared bands of the S7 (7{\mu}m), S11 (11{\mu}m), L15 (15{\mu}m), and L24 (24 {\mu}m). Removal of the artifacts significantly improves the reliability of the ref- erence data for flat-fielding at the L15 and L24 bands. A set of models of the IRC PSFs is also constructed from on-orbit data. These PSFs have extended components that come from diffraction and scattering within the detector arrays. We estimate the aperture correction factors for point sources and the surface brightness correction factors for diffuse sources. We conclude that the surface brightness correction factors range from 0.95 to 0.8, taking account of the extended component of the PSFs. To correct for the extended PSF effects for the study of faint structures, we also develop an image reconstruction method, which consists of the deconvolution with the PSF and the convolution with an appropriate Gaussian. The appropriate removal of the artifacts, improved flat-fielding, and image reconstruction with the extended PSFs enable us to investigate de- tailed structures of extended sources in IRC mid-infrared images.Comment: 35 pages, 15 figures, accepted for publication in PAS
    • 

    corecore