957 research outputs found

    No nearby counterparts to the moving objects in the Hubble Deep Field

    Get PDF
    Ibata et al (1999) have recently discovered faint, moving objects in the Hubble Deep Field. The quantity, magnitudes and proper motions of these objects are consistent with old white dwarfs making up the Galactic dark halo. We review a number of ground-based proper motion surveys in which nearby dark halo white dwarfs might be present, if they have the colours and absolute magnitudes proposed. No such objects have been found, whereas we argue here that several times more would be expected than in the Hubble Deep Field. We conclude it is unlikely that hydrogen atmosphere white dwarfs make up a significant fraction of the halo dark matter. No limits can be placed yet on helium atmosphere dwarfs from optical searches.Comment: 7 pages, 4 figures, MNRAS LaTeX forma

    PERENCANAAN STRUKTUR ATAS GEDUNG MEDIC CENTER RUMAH SAKIT MATA UNDAAN KOTA SURABAYA

    Get PDF
    Studi Perencanaan Struktur Atas Gedung Medic Center Rumah Sakit Mata Undaan Surabaya dalam penelitian ini menggunakan system rangka pemikul momen menengah (SRPMM) beton bertulang. Perhitungan – perhitungan yang dilakukan dalam penelitian ini disesuaikan dengan peraturan yang ada pada SNI 2847 - 2013, SNI 1726 - 2012 dan PPIUG 1983. Perencanaan yang dilakukan pada penelitian ini meliputi perhitungan komponen struktur yang ada pada bangunan tersebut yaitu antara lain pelat, balok dan kolom. Beban gempa pada struktur dihitung dengan metode respon spektra dan analisa beban static ekivalen sedangkan untuk analisa perhitungan gaya – gaya dalam pada komponen bangunan baik struktur primer maupun sekunder menggunakan bantuan program komputer SAP 2000 sebagai acuan perhitungan dan perencanaan. Material yang digunakan yaitu mutu beton sebesar 25 MPa, sedangkan untuk besi tulangan utama menggunakan mutu baja dengan tegangan leleh 320 Mpa dan 240 Mpa untuk besi tulangan geser

    M Dwarfs from Hubble Space Telescope Star Counts. IV

    Get PDF
    We study a sample of about 1400 disk M dwarfs that are found in 148 fields observed with the Wide Field Camera 2 (WFC2) on the Hubble Space Telescope and 162 fields observed with pre-repair Planetary Camera 1 (PC1), of which 95 of the WFC2 fields are newly analyzed. The method of maximum likelihood is applied to derive the luminosity function and the Galactic disk parameters. At first, we use a local color-magnitude relation and a locally determined mass-luminosity relation in our analysis. The results are consistent with those of previous work but with considerably reduced statistical errors. These small statistical errors motivate us to investigate the systematic uncertainties. Considering the metallicity gradient above the Galactic plane, we introduce a modified color-magnitude relation that is a function of Galactic height. The resultant M dwarf luminosity function has a shape similar to that derived using the local color-magnitude relation but with a higher peak value. The peak occurs at MV12M_V \sim 12 and the luminosity function drops sharply toward MV14M_V \sim 14. We then apply a height-dependent mass-luminosity function interpolated from theoretical models with different metallicities to calculate the mass function. Unlike the mass function obtained using local relations, which has a power-law index α=0.47\alpha = 0.47, the one derived from the height-dependent relations tends to be flat (α=0.10\alpha = -0.10). The resultant local surface density of disk M dwarfs (12.2 +/- 1.6 M_sun pc^{-2}) is somewhat smaller than the one obtained using local relations (14.3 +/- 1.3 M_sun pc^{-2}). Our measurement favors a short disk scale length, H = 2.75 +/- 0.16 (statistical) +/- 0.25 (systematic) kpc.Comment: 20 pages, 10 ps figures, accepted for publication in Ap

    Modeling of Charge Transfer Inefficiency in a CCD with High Speed Column Parallel Readout

    Full text link
    Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. An Analytic Model has been developed for the determination of the charge transfer inefficiency (CTI) of a CPCCD. The CTI values determined with the Analytic Model agree largely with those from a full TCAD simulation. The Analytic Model allows efficient study of the variation of the CTI on parameters like readout frequency, operating temperature and occupancy.Comment: 5 pages, 13 figures, presented on behalf of the LCFI Collaboration, proceedings IEEE 2008 Nuclear Science Symposium, Dresden, Germany, and 11th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD08) 2008, Siena, Ital

    M Dwarfs from Hubble Space Telescope Star Counts. V. The I-band Luminosity Function

    Get PDF
    We derive the disk I-band luminosity function from the Zheng et al. sample of \~1400 disk M dwarfs observed with the Hubble Space Telescope. We adopt a Galactic-height-dependent color-magnitude relation to account for the metallicity gradient above the Galactic plane. The resultant I-band luminosity function peaks at M_I~9.5 and drops sharply toward M_I~10.5.Comment: 2 pages, 1 eps figure, submitted to Ap

    Optimal timing of primaquine to reduce Plasmodium falciparum gametocyte carriage when co-administered with artemether-lumefantrine.

    Get PDF
    BACKGROUND: Primaquine is an important gametocytocidal drug that is combined with conventional malaria treatment for prevention of Plasmodium falciparum malaria transmission. Primaquine has been administered together on the first or the last day of conventional treatment but the impact of primaquine timing has never been examined. This study aimed to assess safety, efficacy and optimal timing of single full-dose (0.75 mg/kg) primaquine when added to a standard 6-dose regimen of artemether-lumefantrine (AL). METHODS: In an individual-level randomized controlled trial, enrolled participants who were G6PD normal and had uncomplicated P. falciparum malaria were randomly assigned to receive: AL only; AL and a single 0.75 mg/kg primaquine dose on the first day of AL (day 1); or AL and single 0.75 mg//kg primaquine on the last day of AL (day 3). On days 2, 3, 4, 8, 11 and 15, gametocytes were assessed and quantified by microscope and quantitative nuclear acid sequence based quantification (QT-NASBA). RESULTS: Overall, 111 participants aged between 3 and 17 years were randomly allocated to receive AL only (36) or combined with primaquine on day 1 (38), or primaquine on day 3 (37). Day 4 gametocyte prevalence in AL?+?day 1 primaquine was half the level seen in either AL?+?day 3 primaquine or AL only arm (11% [4/35] vs 26% [8/31] and 27% [8/30], respectively) albeit not statistically significant. A similar trend of lower gametocyte in the AL?+?day 1 primaquine verses AL?+?day 3 primaquine or AL only arm was observed in mean gametocyte density. Mean (sd) haemoglobin level in AL?+?day 3 primaquine arm recovered from -0.42(1.2) g/dl on day 2 to 0.35 (1.5) g/dl on day 15 of follow up. This was not the case in AL only and AL?+?day 1 primaquine arms during the same follow-up period, although the difference was not statistically significant (p?=?318). No serious adverse events reported in the study. Across arms, 23% (26/111) of participants reported a total of 31 mild adverse events and the difference was not statistically significant (p?=?0.477). CONCLUSION: Primaquine administration on the first day of AL is well tolerated and as safe as later administration. Whilst the World Health Organization currently recommends a lower dose of primaquine (0.25 mg/kg), the findings are supportive of early primaquine administration when combined with artemisinin-combination therapy. ClinicalTrials.gov Registration NCT01906788

    1,3-Di-4-pyridylpropane–4,4′-oxy­dibenzoic acid (1/1)

    Get PDF
    The hydro­thermal reaction of Cd(NO3)2·4H2O, 1,3-di-4-pyridylpropane (BPP) and 4,4′-oxydibenzoic acid (OBA) led to the formation of the title compound, C13H14N2·C14H10O5. The asymmetric unit consists of one mol­ecule of OBA and one of BPP. In the OBA mol­ecule, one COOH group is nearly planar with its attached benzene ring [dihedral angle = 0.9 (1)°], while the other COOH group is slightly twisted with a dihedral angle of 10.8 (3)°. The carboxyl groups form strong inter­molecular O—H⋯N hydrogen bonds with N atoms of the pyridine rings in BPP, linking the mol­ecules into zigzag chains

    Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I

    Get PDF
    We report broadband UBV and/or BVRI CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as candidate field horizontal-branch or other A-type stars (FHB/A, N = 576), or candidate low-metallicity stars (N = 1221), from the HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of additional stars from other samples are also reported. These data are being used for several purposes. In the case of the FHB/A candidates they are used to accurately separate the lower-gravity FHB stars from various higher-gravity A-type stars, a subsample that includes the so-called Blue Metal Poor stars, halo and thick-disk blue stragglers, main-sequence A-type dwarfs, and Am and Ap stars. These data are also being used to derive photometric distance estimates to high-velocity hydrogen clouds in the Galaxy and for improved measurements of the mass of the Galaxy. Photometric data for the metal-poor candidates are being used to refine estimates of stellar metallicity for objects with available medium-resolution spectroscopy, to obtain distance estimates for kinematic analyses, and to establish initial estimates of effective temperature for analysis of high-resolution spectroscopy of the stars for which this information now exists.Comment: 22 pages, including 3 figures, 5 tables, and two ascii files of full data, accepted for publication in the Astrophysical Journal (Supplements
    corecore