1,216 research outputs found
Synthesis and crystal structure of calcium hydrogen phosphite, CaHPO3
We thank Kirstie McCombie for collecting the powder pattern, Sarah Ferrandin for collecting the IR spectrum and the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collection. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52–06 N A25396) and Sandia National Laboratories (Contract DE-NA-0003525).Peer reviewedPublisher PD
Ficus insipida subsp. insipida (Moraceae) reveals the role of ecology in the phylogeography of widespread Neotropical rain forest tree species
Aim: To examine the phylogeography of Ficus insipida subsp. insipida in order to investigate patterns of spatial genetic structure across the Neotropics and within Amazonia. Location: Neotropics. Methods: Plastid DNA (trnH-psbA; 410 individuals from 54 populations) and nuclear ribosomal internal transcribed spacer (ITS; 85 individuals from 27 populations) sequences were sampled from Mexico to Bolivia, representing the full extent of the taxon's distribution. Divergence of plastid lineages was dated using a Bayesian coalescent approach. Genetic diversity was assessed with indices of haplotype and nucleotide diversities, and genetic structure was examined using spatial analysis of molecular variance (SAMOVA) and haplotype networks. Population expansion within Amazonia was tested using neutrality and mismatch distribution tests. Results: trnH-psbA sequences yielded 19 haplotypes restricted to either Mesoamerica or Amazonia; six haplotypes were found among ITS sequences. Diversification of the plastid DNA haplotypes began c. 14.6 Ma. Haplotype diversity for trnH-psbA was higher in Amazonia. Seven genetically differentiated SAMOVA groups were described for trnH-psbA, of which two were also supported by the presence of unique ITS sequences. Population expansion was suggested for both markers for the SAMOVA group that contains most Amazonian populations. Main conclusions: Our results show marked population genetic structure in F. insipida between Mesoamerica and Amazonia, implying that the Andes and seasonally dry areas of northern South America are eco-climatic barriers to its migration. This pattern is shared with other widespread pioneer species affiliated to wet habitats, indicating that the ecological characteristics of species may impact upon large-scale phylogeography. Ficus insipida also shows genetic structure in north-western Amazonia potentially related to pre-Pleistocene historical events. In contrast, evident population expansion elsewhere in Amazonia, in particular the presence of genetically uniform populations across the south-west, indicate recent colonization. Our findings are consistent with palaeoecological data that suggest recent post-glacial expansion of Amazonian forests in the south
ALMA 1.3 Millimeter Map of the HD 95086 System
Planets and minor bodies such as asteroids, Kuiper-belt objects and comets
are integral components of a planetary system. Interactions among them leave
clues about the formation process of a planetary system. The signature of such
interactions is most prominent through observations of its debris disk at
millimeter wavelengths where emission is dominated by the population of large
grains that stay close to their parent bodies. Here we present ALMA 1.3 mm
observations of HD 95086, a young early-type star that hosts a directly imaged
giant planet b and a massive debris disk with both asteroid- and Kuiper-belt
analogs. The location of the Kuiper-belt analog is resolved for the first time.
The system can be depicted as a broad (0.84), inclined
(30\arcdeg3\arcdeg) ring with millimeter emission peaked at 2006 au
from the star. The 1.3 mm disk emission is consistent with a broad disk with
sharp boundaries from 1066 to 32020 au with a surface density
distribution described by a power law with an index of --0.50.2. Our deep
ALMA map also reveals a bright source located near the edge of the ring, whose
brightness at 1.3 mm and potential spectral energy distribution are consistent
with it being a luminous star-forming galaxy at high redshift. We set
constraints on the orbital properties of planet b assuming co-planarity with
the observed disk.Comment: accepted for publication in A
Scanning X-ray Diffraction Microscopy for Diamond Quantum Sensing
Understanding nano- and micro-scale crystal strain in CVD diamond is crucial
to the advancement of diamond quantum technologies. In particular, the presence
of such strain and its characterization present a challenge to diamond-based
quantum sensing and information applications -- as well as for future dark
matter detectors where directional information of incoming particles is encoded
in crystal strain. Here, we exploit nanofocused scanning X-ray diffraction
microscopy to quantitatively measure crystal deformation from growth defects in
CVD diamond with high spatial and strain resolution. Combining information from
multiple Bragg angles allows stereoscopic three-dimensional reconstruction of
strained volumes; the diffraction results are validated via comparison to
optical measurements of the strain tensor based on spin-state-dependent
spectroscopy of ensembles of nitrogen vacancy (NV) centers in the diamond. Our
results open a path towards directional detection of dark matter via X-ray
measurement of crystal strain, and provide a new tool for diamond growth
analysis and improvement of defect-based sensing.Comment: 15 pages, 17 figures (incl. Supplemental Material
The Carnegie Supernova Project: The Low-Redshift Survey
Supernovae are essential to understanding the chemical evolution of the
Universe. Type Ia supernovae also provide the most powerful observational tool
currently available for studying the expansion history of the Universe and the
nature of dark energy. Our basic knowledge of supernovae comes from the study
of their photometric and spectroscopic properties. However, the presently
available data sets of optical and near-infrared light curves of supernovae are
rather small and/or heterogeneous, and employ photometric systems that are
poorly characterized. Similarly, there are relatively few supernovae whose
spectral evolution has been well sampled, both in wavelength and phase, with
precise spectrophotometric observations. The low-redshift portion of the
Carnegie Supernova Project (CSP) seeks to remedy this situation by providing
photometry and spectrophotometry of a large sample of supernovae taken on
telescope/filter/detector systems that are well understood and well
characterized. During a five-year program which began in September 2004, we
expect to obtain high-precision u'g'r'i'BVYJHKs light curves and optical
spectrophotometry for about 250 supernovae of all types. In this paper we
provide a detailed description of the CSP survey observing and data reduction
methodology. In addition, we present preliminary photometry and spectra
obtained for a few representative supernovae during the first observing
campaign.Comment: 45 pages, 13 figures, 3 tables, accepted by PAS
Combined Inflammatory and Metabolic Defects Reflected by Reduced Serum Protein Levels in Patients with Buruli Ulcer Disease
Buruli ulcer is a skin disease caused by Mycobacterium ulcerans that is spreading in tropical countries, with major public health and economic implications in West Africa. Multi-analyte profiling of serum proteins in patients and endemic controls revealed that Buruli ulcer disease down-regulates the circulating levels of a large array of inflammatory mediators, without impacting on the leukocyte composition of peripheral blood. Notably, several proteins contributing to acute phase reaction, lipid metabolism, coagulation and tissue remodelling were also impacted. Their down-regulation was selective and
persisted after the elimination of bacteria with antibiotic therapy. It involved proteins with various functions and origins, suggesting that M. ulcerans infection causes global and chronic defects in the host’s protein metabolism. Accordingly, patients had reduced levels of total serum proteins and blood urea, in the absence of signs of malnutrition, or functional failure of liver or kidney. Interestingly, slow healers had deeper metabolic and coagulation defects at the start of antibiotic therapy. In addition to providing novel insight into Buruli ulcer pathogenesis, our study therefore identifies a unique
proteomic signature for this disease
The Carnegie-Chicago Hubble Program. VIII. An Independent Determination of the Hubble Constant Based on the Tip of the Red Giant Branch
We present a new and independent determination of the local value of the
Hubble constant based on a calibration of the Tip of the Red Giant Branch
(TRGB) applied to Type Ia supernovae (SNeIa). We find a value of Ho = 69.8 +/-
0.8 (+/-1.1\% stat) +/- 1.7 (+/-2.4\% sys) km/sec/Mpc. The TRGB method is both
precise and accurate, and is parallel to, but independent of the Cepheid
distance scale. Our value sits midway in the range defined by the current
Hubble tension. It agrees at the 1.2-sigma level with that of the Planck 2018
estimate, and at the 1.7-sigma level with the SHoES measurement of Ho based on
the Cepheid distance scale. The TRGB distances have been measured using deep
Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging of
galaxy halos. The zero point of the TRGB calibration is set with a distance
modulus to the Large Magellanic Cloud of 18.477 +/- 0.004 (stat) +/-0.020 (sys)
mag, based on measurement of 20 late-type detached eclipsing binary (DEB)
stars, combined with an HST parallax calibration of a 3.6 micron Cepheid
Leavitt law based on Spitzer observations. We anchor the TRGB distances to
galaxies that extend our measurement into the Hubble flow using the recently
completed Carnegie Supernova Project I sample containing about 100
well-observed SNeIa. There are several advantages of halo TRGB distance
measurements relative to Cepheid variables: these include low halo reddening,
minimal effects of crowding or blending of the photometry, only a shallow
(calibrated) sensitivity to metallicity in the I-band, and no need for multiple
epochs of observations or concerns of different slopes with period. In
addition, the host masses of our TRGB host-galaxy sample are higher on average
than the Cepheid sample, better matching the range of host-galaxy masses in the
CSP distant sample, and reducing potential systematic effects in the SNeIa
measurements.Comment: 60 pages, 20 figures, accepted for publication in the Astrophysical
Journa
The Distance to NGC 1316 (Fornax A) From Observations of Four Type Ia Supernovae
The giant elliptical galaxy NGC 1316 (Fornax A) is a well-studied member of
the Fornax Cluster and a prolific producer of Type Ia supernovae, having hosted
four observed events since 1980. Here we present detailed optical and
near-infrared light curves of the spectroscopically normal SN 2006dd. These
data are used, along with previously published photometry of the normal SN
1980N and SN 1981D, and the fast-declining, low-luminosity SN 2006mr, to
compute independent estimates of the host reddening for each supernova, and the
distance to NGC 1316. From the three normal supernovae, we find a distance of
17.8 +/- 0.3 (random) +/- 0.3 (systematic) Mpc for Ho = 72. Distance moduli
derived from the "EBV" and Tripp methods give values that are mutually
consistent to 4 -- 8%. Moreover, the weighted means of the distance moduli for
these three SNe for three methods agree to within 3%. This consistency is
encouraging and supports the premise that Type Ia supernovae are reliable
distance indicators at the 5% precision level or better. On the other hand, the
two methods used to estimate the distance of the fast-declining SN 2006mr both
yield a distance to NGC 1316 which is 25-30% larger. This disparity casts doubt
on the suitability of fast-declining events for estimating extragalactic
distances. Modest-to-negligible host galaxy reddening values are derived for
all four supernovae. Nevertheless, two of them (SN 2006dd and SN 2006mr) show
strong NaID interstellar lines in the host galaxy system. The strength of this
absorption is completely inconsistent with the small reddening values derived
from the supernova light curves if the gas in NGC 1316 is typical of that found
in the interstellar medium of the Milky Way. In addition, the equivalent width
of the NaID lines in SN 2006dd appear to have weakened significantly some
100-150 days after explosion.Comment: 50 pages, 13 figures, 10 tables; constructive comments welcome.
Accepted for publication in A
Imaging and Demography of the Host Galaxies of High-Redshift Type Ia Supernovae
We present the results of a study of the host galaxies of high redshift Type
Ia supernovae (SNe Ia). We provide a catalog of 18 hosts of SNe Ia observed
with the Hubble Space Telescope (HST) by the High-z Supernova Search Team
(HZT), including images, scale-lengths, measurements of integrated (Hubble
equivalent) BVRIZ photometry in bands where the galaxies are brighter than m ~
25 mag, and galactocentric distances of the supernovae. We compare the
residuals of SN Ia distance measurements from cosmological fits to measurable
properties of the supernova host galaxies that might be expected to correlate
with variable properties of the progenitor population, such as host galaxy
color and position of the supernova. We find mostly null results; the current
data are generally consistent with no correlations of the distance residuals
with host galaxy properties in the redshift range 0.42 < z < 1.06. Although a
subsample of SN hosts shows a formally significant (3-sigma) correlation
between apparent V-R host color and distance residuals, the correlation is not
consistent with the null results from other host colors probed by our largest
samples. There is also evidence for the same correlations between SN Ia
properties and host type at low redshift and high redshift. These similarities
support the current practice of extrapolating properties of the nearby
population to high redshifts pending more robust detections of any correlations
between distance residuals from cosmological fits and host properties.Comment: 35 pages, 12 figures, 4 tables, accepted for publication in A
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