6,864 research outputs found
Monte Carlo Method for Calculating Oxygen Abundances and Their Uncertainties from Strong-Line Flux Measurements
We present the open-source Python code pyMCZ that determines oxygen abundance
and its distribution from strong emission lines in the standard metallicity
calibrators, based on the original IDL code of Kewley & Dopita (2002) with
updates from Kewley & Ellison (2008), and expanded to include more recently
developed calibrators. The standard strong-line diagnostics have been used to
estimate the oxygen abundance in the interstellar medium through various
emission line ratios in many areas of astrophysics, including galaxy evolution
and supernova host galaxy studies. We introduce a Python implementation of
these methods that, through Monte Carlo sampling, better characterizes the
statistical oxygen abundance confidence region including the effect due to the
propagation of observational uncertainties. These uncertainties are likely to
dominate the error budget in the case of distant galaxies, hosts of cosmic
explosions. Given line flux measurements and their uncertainties, our code
produces synthetic distributions for the oxygen abundance in up to 15
metallicity calibrators simultaneously, as well as for E(B-V), and estimates
their median values and their 68% confidence regions. We test our code on
emission line measurements from a sample of nearby supernova host galaxies (z <
0.15) and compare our metallicity results with those from previous methods. Our
metallicity estimates are consistent with previous methods but yield smaller
statistical uncertainties. Systematic uncertainties are not taken into account.
We offer visualization tools to assess the spread of the oxygen abundance in
the different calibrators, as well as the shape of the estimated oxygen
abundance distribution in each calibrator, and develop robust metrics for
determining the appropriate Monte Carlo sample size. The code is open access
and open source and can be found at https://github.com/nyusngroup/pyMCZ
(Abridged)Comment: Accepted for publication in Astronomy& Computing, 2016. The code is
open-access, open-source, and suggestions and improvements are welcome! The
python module is available at https://github.com/nyusngroup/pyMC
Urinary excretion of RAS, BMP, and WNT pathway components in diabetic kidney disease.
Abstract The renin-angiotensin system (RAS), bone morphogenetic protein (BMP), and WNT pathways are involved in pathogenesis of diabetic kidney disease (DKD). This study characterized assays for urinary angiotensinogen (AGT), gremlin-1, and matrix metalloproteinase 7 (MMP-7), components of the RAS, BMP, and WNT pathways and examined their excretion in DKD. We measured urine AGT, gremlin-1, and MMP-7 in individuals with type 1 diabetes and prevalent DKD (n = 20) or longstanding (n = 61) or new-onset (n = 10) type 1 diabetes without DKD. These urine proteins were also quantified in type 2 DKD (n = 11) before and after treatment with candesartan. The utilized immunoassays had comparable inter- and intra-assay and intraindividual variation to assays used for urine albumin. Median (IQR) urine AGT concentrations were 226.0 (82.1, 550.3) and 13.0 (7.8, 20.0) μg/g creatinine in type 1 diabetes with and without DKD, respectively (P < 0.001). Median (IQR) urine gremlin-1 concentrations were 48.6 (14.2, 254.1) and 3.6 (1.7, 5.5) μg/g, respectively (P < 0.001). Median (IQR) urine MMP-7 concentrations were 6.0 (3.8, 10.5) and 1.0 (0.4, 2.9) μg/g creatinine, respectively (P < 0.001). Treatment with candesartan was associated with a reduction in median (IQR) urine AGT/creatinine from 23.5 (1.6, 105.1) to 2.0 (1.4, 13.7) μg/g, which did not reach statistical significance. Urine gremlin-1 and MMP-7 excretion did not decrease with candesartan. In conclusion, DKD is characterized by markedly elevated urine AGT, MMP-7, and gremlin-1. AGT decreased in response to RAS inhibition, suggesting that this marker reflects therapeutic response. Urinary components of the RAS, BMP, and WNT pathways may identify risk of DKD and aid development of novel therapeutics
Study Fishing Ground In Kampar Kiri River Gunung Sahilan Village, Gunung Sahilan District, Kampar Regency, Province Of Riau
This study was conducted in May 2015 during the dry season in Kampar Kiri river Gunung Sahilan village, Gunung Sahilan district, Kampar regency, province of Riau. Purpose of this study was to obtain data on environmental parameters become the benchmark fishing grounds and fishing activity. Environmental parameters measured are temperature, current speed, brightness, depth, acidity (pH) and dissolved oxygen. After doing this research is that the condition of the Kampar Kiri river Gunung Sahilan village still quite good and still support for life of organisms that were in it and deserves to fishing activities in these waters
Optical Spectra of 73 Stripped-Envelope Core-Collapse Supernovae
We present 645 optical spectra of 73 supernovae (SNe) of Types IIb, Ib, Ic,
and broad-lined Ic. All of these types are attributed to the core collapse of
massive stars, with varying degrees of intact H and He envelopes before
explosion. The SNe in our sample have a mean redshift = 4200 km/s. Most of
these spectra were gathered at the Harvard-Smithsonian Center for Astrophysics
(CfA) between 2004 and 2009. For 53 SNe, these are the first published spectra.
The data coverage range from mere identification (1-3 spectra) for a few SNe to
extensive series of observations (10-30 spectra) that trace the spectral
evolution for others, with an average of 9 spectra per SN. For 44 SNe of the 73
SNe presented here, we have well-determined dates of maximum light to determine
the phase of each spectrum. Our sample constitutes the most extensive spectral
library of stripped-envelope SNe to date. We provide very early coverage (as
early as 30 days before V-band max) for photospheric spectra, as well as
late-time nebular coverage when the innermost regions of the SNe are visible
(as late as 2 years after explosion, while for SN1993J, we have data as late as
11.6 years). This data set has homogeneous observations and reductions that
allow us to study the spectroscopic diversity of these classes of stripped SNe
and to compare these to SNe associated with gamma-ray bursts. We undertake
these matters in follow-up papers.Comment: Published by the Astronomical Journal in May 2015. All spectra are
publicly available at the CfA SN archive:
http://www.cfa.harvard.edu/supernova/SNarchive.html . A companion paper on
constructing SNID templates based on these spectra is by Liu & Modjaz (2014)
and the resulting SNID templates are available from the NYU website:
http://cosmo.nyu.edu/SNYU/spectra
- …
