965 research outputs found
Testing for redshift evolution of Type Ia supernovae using the strongly lensed PS1-10afx at
The light from distant supernovae (SNe) can be magnified through
gravitational lensing when a foreground galaxy is located along the line of
sight. This line-up allows for detailed studies of SNe at high redshift that
otherwise would not be possible. Spectroscopic observations of lensed
high-redshift Type Ia supernovae (SNe Ia) are of particular interest since they
can be used to test for evolution of their intrinsic properties. The use of SNe
Ia for probing the cosmic expansion history has proven to be an extremely
powerful method for measuring cosmological parameters. However, if systematic
redshift-dependent properties are found, their usefulness for future surveys
could be challenged. We investigate whether the spectroscopic properties of the
strongly lensed and very distant SN Ia PS1-10afx at deviates from the
well-studied populations of normal SNe Ia at nearby or intermediate distance.
We created median spectra from nearby and intermediate-redshift
spectroscopically normal SNe Ia from the literature at -5 and +1 days from
light-curve maximum. We then compared these median spectra to those of
PS1-10afx. We do not find signs of spectral evolution in PS1-10afx. The
observed deviation between PS1-10afx and the median templates are within what
is found for SNe at low- and intermediate-redshift. There is a noticeable broad
feature centred at ~\AA{}, which is present only to a
lesser extent in individual low and intermediate redshift SN Ia spectra. From a
comparison with a recently developed explosion model, we find this feature to
be dominated by iron peak elements, in particular, singly ionized cobalt and
chromium.Comment: accepted for publication in section 4. Extragalactic astronomy of
Astronomy and Astrophysic
Effect of Tannery Effluent and Domestic Wastewater Irrigation on Growth Parameter and Flower Yield of Marigold
Pot culture and field experiments were conducted at the Common Effluent Treatment Plant (CETP), Dindigul, Tamil Nadu, India to study the effect of irrigating treated tannery effluent and domestic wastewater with amendments on growth characters and flower yield of marigold. The pot culture was laid out in a factorial completely randomized design and field experiment laid out in factorial randomized block design with four replications. The results revealed that the mixing proportion of 25% treated tannery effluent (TTE) + 75% domestic wastewater (DWW) recorded taller plant height, higher root length, dry matter production and flower yield compared to other mixing proportions. The yield reduction under 25% TTE + 75% DWW was 14.62% (pot culturre) and 15.85% (field experiment) compared to normal water. This yield reduction was lesser level when compared to other mixing proportion. Regarding amendments, addition of gypsum showed better performance compared to Vesicular arbuscular mycorrhiza (VAM) and control (without amendments). Hence, Irrigation of 25% TTE with 75% DWW (1:3 ratio) with gypsum application for marigold will help to effective exploitation of tannery effluent and wastewater through enhanced yield and minimizing environmental pollution compared to 100% TTE
HDL-C: Does it matter? An update on novel HDL-directed pharmaco-therapeutic strategies.
It has long been recognized that elevated levels of low-density lipoprotein cholesterol (LDL-C) increase the risk of cardiovascular disease (CHD) and that pharmacologic therapy to decrease LDL-C significantly reduces cardiovascular events. Despite the effectiveness of statins for CHD risk reduction, even optimal LDL-lowering therapy alone fails to avert 60% to 70% of CHD cases. A low plasma concentration of high-density lipoprotein cholesterol (HDL-C) is also associated with increased risk of CHD. However, the convincing epidemiologic data linking HDL cholesterol (HDL-C) to CHD risk in an inverse correlation has not yet translated into clinical trial evidence supporting linearity between HDL-C increases and CHD risk reduction. It is becoming clear that a functional HDL is a more desirable target than simply increasing HDL-C levels. Discoveries in the past decade have shed light on the complex metabolic and antiatherosclerotic pathways of HDL. These insights, in turn, have fueled the development of new HDL-targeted drugs, which can be classified according to four different therapeutic approaches: directly augmenting the concentration of apolipoprotein A-I (apo A-I), the major protein constituent of HDL; indirectly augmenting the concentration of apo A-I and HDL cholesterol; mimicking the functionality of apo A-I and enhancing reverse cholesterol transport. This review discusses the latest in novel HDL directed therapeutic strategies
Constraints on the origin of the first light from SN2014J
We study the very early lightcurve of supernova 2014J (SN 2014J) using the
high-cadence broad-band imaging data obtained by the Kilodegree Extremely
Little Telescope (KELT), which fortuitously observed M 82 around the time of
the explosion, starting more than two months prior to detection, with up to 20
observations per night. These observations are complemented by observations in
two narrow-band filters used in an H survey of nearby galaxies by the
intermediate Palomar Transient Factory (iPTF) that also captured the first days
of the brightening of the \sn. The evolution of the lightcurves is consistent
with the expected signal from the cooling of shock heated material of large
scale dimensions, \gsim 1 R_{\odot}. This could be due to heated material of
the progenitor, a companion star or pre-existing circumstellar environment,
e.g., in the form of an accretion disk. Structure seen in the lightcurves
during the first days after explosion could also originate from radioactive
material in the outer parts of an exploding white dwarf, as suggested from the
early detection of gamma-rays. The model degeneracy translates into a
systematic uncertainty of days on the estimate of the first light
from SN 2014J.Comment: Accepted by ApJ. Companion paper by Siverd et al, arXiv:1411.415
Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2–2 μm. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B − V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R_V. In particular, we note that for the two SNe with E(B − V) ≳ 1 mag, for which the colour excess is dominated by dust extinction, we find R_V = 1.4 ± 0.1 and RV = 2.8 ± 0.1. Adding UV photometry reduces the uncertainty of fitted R_V by ∼50 per cent allowing us to also measure R_V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe
Earlier surgical intervention in congenital heart disease results in better outcome and resource utilization
Background:Congenital heart disease (CHD) accounts for a major proportion of disease in the pediatric age group. The objective of the study was to estimate the cost of illness associated with CHD pre, intra and postoperatively, among Patients referred to a tertiary care hospital in Karachi, Pakistan. This is the first study conducted to estimate the cost of managing CHD in Pakistan.
Methods:
A prevalence based cost of illness Study Design was used to estimate the cost of cardiac surgery (corrective & palliative) for congenital heart defects in children Results:The mean age at the time of surgery in group A (1-12 mo age) was 6.08 +/- 2.80 months and in group B (1-5 yrs) was 37.10 +/- 19.94 months. The cost of surgical admission was found to be significantly higher in the older group, p = 0.001. The total number and cost of post-operative outPatient visits was also higher in group B, p = 0.003. Pre and post operative hospital admissions were not found to be significantly different among the two groups, p = 0.166 and 0.627, respectively. The number of complications were found to be different between the two groups (p = 0.019). Majority of these were contributed by hemorrhage and post-operative seizures.
Conclusion:
This study concluded that significant expenditure is incurred by people with CHD, with the implication that resources could be saved by earlier detection and awareness campaigns
Tetralogy of Fallot with absent pulmonary valve syndrome; appropriate surgical strategies
Abstract OBJECTIVE:
To evaluate patients presenting with Tetralogy of Fallot with absent pulmonary valve syndrome to a tertiary care hospital and their surgical management. METHODS:
The retrospective study was conducted at Congenital Cardiac Services, Aga Khan University Hospital, Karachi, Pakistan, and comprised data of Tetralogy of Fallot patients between April 2007 and June 2012. Data was analysed together with follow-up echocardiography. Variables assessed included demographics, imaging, operative technique, complications, post-operative recovery and follow-up echocardiography. SPSS 17 was used for statistical analysis. RESULTS:
Of the 204 patients, 6 (3%) had undergone surgical correction for Tetralogy of Fallot with absent pulmonary valve syndrome. All 6(100%) patients underwent complete repair. Median age for surgery was 8.5 years (range: 0.5-29 years). Of the different surgical strategies used, Contegra and Bioprosthetic valve placement had satisfactory outcome with minimal gradient at Right Ventricular Outflow Tract, good ventricular function and mild valvular regurgitation. One (16.6%) patient with Trans Annular Patch developed post-operative Right Ventricle Outflow Tract gradient of 80mmHg with moderate pulmonary regurgitation. One (16.6%) patient with monocusp valve developed free pulmonary regurgitation at 6 months. The other 4(66.6%) patients are currently free from any complications or re-intervention. CONCLUSIONS:
Early surgery is preferred in symptomatic patients. The repair depends upon achieving integrity of pulmonary circulation which is best achieved by using right ventricle to pulmonary artery conduit or inserting a pulmonary valve
Probing gas and dust in the tidal tail of NGC 5221 with the type Ia supernova iPTF16abc
Context. Type Ia supernovae (SNe Ia) can be used to address numerous
questions in astrophysics and cosmology. Due to their well known spectral and
photometric properties, SNe Ia are well suited to study gas and dust along the
lines-of-sight to the explosions. For example, narrow Na I D and Ca II H&K
absorption lines can be studied easily, because of the well-defined spectral
continuum of SNe Ia around these features. Aims. We study the gas and dust
along the line-of-sight to iPTF16abc, which occurred in an unusual location, in
a tidal arm, 80 kpc from centre of the galaxy NGC 5221. Methods. Using a
time-series of high-resolution spectra, we examine narrow Na I D and Ca II H&K
absorption features for variations in time, which would be indicative for
circumstellar (CS) matter. Furthermore, we take advantage of the well known
photometric properties of SNe Ia to determine reddening due to dust along the
line-of-sight. Results. From the lack of variations in Na I D and Ca II H&K, we
determine that none of the detected absorption features originate from the CS
medium of iPTF16abc. While the Na I D and Ca II H&K absorption is found to be
optically thick, a negligible amount of reddening points to a small column of
interstellar dust. Conclusions. We find that the gas along the line-of-sight to
iPTF16abc is typical of what might be found in the interstellar medium (ISM)
within a galaxy. It suggests that we are observing gas that has been tidally
stripped during an interaction of NGC 5221 with one of its neighbouring
galaxies in the past years. In the future, the gas clouds could
become the locations of star formation. On a longer time scale, the clouds
might diffuse, enriching the circum-galactic medium (CGM) with metals. The gas
profile along the line-of-sight should be useful for future studies of the
dynamics of the galaxy group containing NGC 5221.Comment: 8 pages, 6 figure
Best assessment practices of final year engineering projects in Australia
Purpose:The focus of the paper is to explore the best practices for the delivery of final year engineering project. Students use their own initiatives to accomplish practical design projects in their final year of engineering. Each academia proposes different ways of project approaches that should satisfy engineering accreditation requirements for capstone projects. This paper analyses and compares various undergraduate final year engineering project approaches of different universities in Australia. From this case study analysis, this research will explore the best assessment practice for the delivery of final year project. Design/Methodology: Through desktop analysis methodology, this paper will analyse six universities in Australia who are practicing different approaches in their undergraduate final year engineering project. This analysis will look in to the various types of final year projects undertaken, their learning outcomes, teaching methods and assessment measures. Findings: From these 6 case studies, this paper will provide a report on its implementation and assessment impact on final year projects based on the analysed results of qualitative review of course units in undergraduate programs. Conclusions: This paper shows the desktop analysis data and compared the six case studies of Australian universities. The above-summarized different final year engineering project approaches were extremely successful in identifying and promoting creativity and innovation through final year projects. From the comparison, it is clearly shown that Deakin University practices one of best assessment methods for the delivery of final year engineering project
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