338 research outputs found
Narrow band survey for intragroup light in the Leo HI cloud. Constraints on the galaxy background contamination in imaging surveys for intracluster planetary nebulae
We have observed emission line objects located in a 0.26 deg^2 field in the
M96 (Leo) group, coincident with the intergalactic HI cloud. The emission line
objects were selected using the same procedure as used for the search for
intracluster planetary nebulae in the Virgo cluster, and their m_5007
luminosity function has a bright cut-off ~1.2 magnitude fainter than for the
PNLF associated with the elliptical galaxies in the M96 group.Therefore the
vast majority of these emission line objects are compatible with not being
intragroup planetary nebulae at the Leo group distance of 10 Mpc. Spectroscopic
follow-up of two emission line objects in this Leo field showed that indeed
these do not have the [OIII] doublet expected for a real PN. The brighter
source is identified as a starburst object at redshift z = 3.128, because of a
second emission in the near infrared, identified as FeII (\lambda 2220 AA).
From these data we derive three main results: (i) from the absence of PN we
can determine a more stringent upper limit to the surface brightness in any old
stellar population associated with the Leo HI cloud. (ii) This translates to an
upper limit of 1.6% for the fraction of luminosity in a diffuse intragroup
component in the densest 3 x 2 deg area of the Leo group,relative to the light
in galaxies. (iii) Using this Leo field as a blank field, we derive an average
fraction of 13.6% background emission line objects that enter in surveys of
Virgo intracluster PN. The small fraction confirms the validity of the
selection criteria for intracluster PN candidates in Virgo.Comment: 11 pages, in press on Astronomy & Astrophysic
Simultaneous quantification of 12 different nucleotides and nucleosides released from renal epithelium and in human urine samples using ion-pair reversed-phase HPLC
Nucleotides and nucleosides are not only involved in cellular metabolism but also act extracellularly via P1 and P2 receptors, to elicit a wide variety of physiological and pathophysiological responses through paracrine and autocrine signalling pathways. For the first time, we have used an ion-pair reversed-phase high-performance liquid chromatography ultraviolet (UV)-coupled method to rapidly and simultaneously quantify 12 different nucleotides and nucleosides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, adenosine, uridine triphosphate, uridine diphosphate, uridine monophosphate, uridine, guanosine triphosphate, guanosine diphosphate, guanosine monophosphate, guanosine): (1) released from a mouse renal cell line (M1 cortical collecting duct) and (2) in human biological samples (i.e., urine). To facilitate analysis of urine samples, a solid-phase extraction step was incorporated (overall recovery rate ? 98 %). All samples were analyzed following injection (100 ?l) into a Synergi Polar-RP 80 Å (250 × 4.6 mm) reversed-phase column with a particle size of 10 ?m, protected with a guard column. A gradient elution profile was run with a mobile phase (phosphate buffer plus ion-pairing agent tetrabutylammonium hydrogen sulfate; pH 6) in 2-30 % acetonitrile (v/v) for 35 min (including equilibration time) at 1 ml min(-1) flow rate. Eluted compounds were detected by UV absorbance at 254 nm and quantified using standard curves for nucleotide and nucleoside mixtures of known concentration. Following validation (specificity, linearity, limits of detection and quantitation, system precision, accuracy, and intermediate precision parameters), this protocol was successfully and reproducibly used to quantify picomolar to nanomolar concentrations of nucleosides and nucleotides in isotonic and hypotonic cell buffers that transiently bathed M1 cells, and urine samples from normal subjects and overactive bladder patients
Development of CCD cameras for soft x-ray imaging at the National Ignition Facility
Abstract not provide
Search for Resonant Decays at Belle
We report measurements and searches for resonant decays where is a
meson or
the X(3872) particle.Comment: accepted by Physics Letters
Large Synoptic Survey Telescope: From Science Drivers To Reference Design
In the history of astronomy, major advances in our understanding of the Universe have come from dramatic improvements in our ability to accurately measure astronomical quantities. Aided by rapid progress in information technology, current sky surveys are changing the way we view and study the Universe. Next-generation surveys will maintain this revolutionary progress. We focus here on the most ambitious survey currently planned in the visible band, the Large Synoptic Survey Telescope (LSST). LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: constraining dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. It will be a large, wide-field ground-based system designed to obtain multiple images covering the sky that is visible from Cerro Pach'{o}n in Northern Chile. The current baseline design, with an 8.4, m (6.5, m effective) primary mirror, a 9.6 deg field of view, and a 3,200 Megapixel camera, will allow about 10,000 square degrees of sky to be covered using pairs of 15-second exposures in two photometric bands every three nights on average. The system is designed to yield high image quality, as well as superb astrometric and photometric accuracy. The survey area will include 30,000 deg with , and will be imaged multiple times in six bands, , covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 deg region about 1000 times in the six bands during the anticipated 10 years of operation. These data will result in databases including 10 billion galaxies and a similar number of stars, and will serve the majority of science programs. The remaining 10\% of the observing time will be allocated to special programs such as Very Deep and Very Fast time domain surveys. We describe how the LSST science drivers led to these choices of system parameters
Measurement of Branching Fraction and Direct CP Asymmetry in B0-->rho0 pi0 Decays
We report a measurement of the decay B0 --> rho0 pi0, using 386 x 10^6 BB-bar
pairs collected at the Upsilon(4S) resonance with the Belle detector at the
KEKB asymmetric-energy e+e- collider. We detect 51^{+14}_{-13} signal events
with a significance of 4.2 standard deviations, including systematic
uncertainties, and measure the branching fraction to be B(B0 --> rho0 pi0) =
(3.12^{+0.88}_{-0.82} (stat) +/- 0.33 (syst) ^{+0.50}_{-0.68} (model)) x
10^{-6}. We also perform the first measurement of direct CP violating asymmetry
in this mode.Comment: 5 pages, 2 figures, accepted in Physical Review
Tree-Ring-Reconstructed Summer Temperatures from Northwestern North America during the Last Nine Centuries*
Northwestern North America has one of the highest rates of recent temperature increase in the world, but the putative “divergence problem” in dendroclimatology potentially limits the ability of tree-ring proxy data at high latitudes to provide long-term context for current anthropogenic change. Here, summer temperatures are reconstructed from a Picea glauca maximum latewood density (MXD) chronology that shows a stable relationship to regional temperatures and spans most of the last millennium at the Firth River in northeastern Alaska. The warmest epoch in the last nine centuries is estimated to have occurred during the late twentieth century, with average temperatures over the last 30 yr of the reconstruction developed for this study [1973–2002 in the Common Era (CE)] approximately 1.3° ± 0.4°C warmer than the long-term preindustrial mean (1100–1850 CE), a change associated with rapid increases in greenhouse gases. Prior to the late twentieth century, multidecadal temperature fluctuations covary broadly with changes in natural radiative forcing. The findings presented here emphasize that tree-ring proxies can provide reliable indicators of temperature variability even in a rapidly warming climate
Small donors in world politics: The role of trust funds in the foreign aid policies of Central and Eastern European donors
The Central and Eastern European (CEE) EU member states have emerged as new donors of international development assistance since the turn of the millennium. The literature has tended to focus on the bilateral components of these policies, and neglected CEE multilateral aid. This paper contributes to filling this gap by examining how and why CEE donors contribute to trust funds operated by multilateral donors. The aim of the paper is twofold: First, it provides a descriptive account of how CEE countries use trust funds in the allocation of their foreign aid. Second, it explains this allocation using data from qualitative interviews with CEE officials. CEE countries make much less use of trust funds than might be expected. This is due not only to the loss of visibility and control over their resources, but also to how CEE companies and non-governmental organisations (NGOs) rarely achieve funding successes at multilateral organisations
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
The Frequency of Intrinsic X-ray Weakness Among Broad Absorption Line Quasars
We present combined Chandra observations of seven broad absorption line (BAL) quasars selected from the Large Bright
Quasar Survey (LBQS). These seven objects are high-ionization BAL (HiBAL)
quasars, and they were undetected in the Chandra hard band ( keV) in
previous observations. The stacking analyses of previous Chandra observations
suggested that these seven objects likely contain some candidates for
intrinsically X-ray weak BAL quasars. With the new Chandra observations, six
targets are detected. We calculate their effective power-law photon indices and
hard-band flux weakness, and find that two objects, LBQS and LBQS
, show soft/steep spectral shapes ( and ) and significant X-ray weakness in
the hard band (by factors of 15 and 12). We conclude that the two
HiBAL quasars are good candidates for intrinsically X-ray weak BAL quasars. The
mid-infrared-to-UV spectral energy distributions (SEDs) of the two candidates
are consistent with those of typical quasars. We constrain the fraction of
intrinsically X-ray weak AGNs among HiBAL quasars to be
(), and we estimate it is () among the
general BAL quasar population. Such a fraction is considerably larger than the
fraction among non-BAL quasars, and we suggest that intrinsically X-ray weak
quasars are preferentially observed as BAL quasars. Intrinsically X-ray weak
AGNs likely comprise a small minority of the luminous type 1 AGN population,
and they should not affect significantly the completeness of these AGNs found
in deep X-ray surveys.Comment: 11 pages, 6 figures, accepted for publication in Ap
- …