8,598 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
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
How Much Can We Trust Major Element Quantification in Bioapatite Investigation?
Bioapatite is probably the key factor in the unreplicated success of vertebrates. Chemical data on bioapatite composition can be achieved on a solid sample by using different analytical tools such as spectroscopic and spectrometric methods. As analytical outputs can be affected by the physical-chemical characteristics of the sample matrix, an internal standard is usually required to correct and validate the results. Bioapatite lattice can accommodate iso- and heterovalent substitutions during life or diagenesis varying its chemical composition through (geological) time. If on the one hand, this makes bioapatite a unique archive of physical and chemical information for both the living cycle and the events occurring after death, on the other, it excludes the identification of a sole internal standard. Here, we propose a method to measure major element concentration with specific care for P, Ca, Mg, Na, K, Si, Al, and Fe, which are the main substituent atoms in bioapatite, through homemade matrix-matched external calibration standards for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). We tested the method on living and fossil shark teeth, critically comparing the results obtained using other analytical techniques and certified external standards. We demonstrated that matrix-matched calibration in LA-ICPMS is mandatory for obtaining a reliable chemical characterization even if factors such as matrix aggregation variability, diverse presence of volatile compounds, the fossilization footprint, and the instrumental variability can represent further variability parameters
Credit bureaus between risk-management, creditworthiness assessment and prudential supervision
"This text may be downloaded for personal research purposes only. Any additional reproduction for other purposes, whether in hard copy or electronically, requires the consent of the author. If cited or quoted, reference should be made to the full name of the author, the title, the working paper or other series, the year, and the publisher."This paper discusses the role and operations of consumer Credit Bureaus in the European Union in the context of the economic theories, policies and law within which they work. Across Europe there is no common practice of sharing the credit data of consumers which can be used for several purposes. Mostly, they are used by the lending industry as a practice of creditworthiness assessment or as a risk-management tool to underwrite borrowing decisions or price risk. However, the type, breath, and depth of information differ greatly from country to country. In some Member States, consumer data are part of a broader information centralisation system for the prudential supervision of banks and the financial system as a whole. Despite EU rules on credit to consumers for the creation of the internal market, the underlying consumer data infrastructure remains fragmented at national level, failing to achieve univocal, common, or defined policy objectives under a harmonised legal framework. Likewise, the establishment of the Banking Union and the prudential supervision of the Euro area demand standardisation and convergence of the data used to measure debt levels, arrears, and delinquencies. The many functions and usages of credit data suggest that the policy goals to be achieved should inform the legal and institutional framework of Credit Bureaus, as well as the design and use of the databases. This is also because fundamental rights and consumer protection concerns arise from the sharing of credit data and their expanding use
Segond's fracture: a biomechanical cadaveric study using navigation
Background Segond’s fracture is a well-recognised radiological
sign of an anterior cruciate ligament (ACL) tear.
While previous studies evaluated the role of the anterolateral
ligament (ALL) and complex injuries on rotational
stability of the knee, there are no studies on the biomechanical
effect of Segond’s fracture in an ACL deficient
knee. The aim of this study was to evaluate the effect of a
Segond’s fracture on knee rotation stability as evaluated by
a navigation system in an ACL deficient knee.
Materials and methods Three different conditions were
tested on seven knee specimens: intact knee, ACL deficient
knee and ACL deficient knee with Segond’s fracture. Static
and dynamic measurements of anterior tibial translation
(ATT) and axial tibial rotation (ATR) were recorded by the
navigation system (2.2 OrthoPilot ACL navigation system
B. Braun Aesculap, Tuttlingen, Germany).
Results Static measurements at 30 showed that the mean
ATT at 30 of knee flexion was 5.1 ± 2.7 mm in the ACL
intact condition, 14.3 ± 3.1 mm after ACL cut
(P = 0.005), and 15.2 ± 3.6 mm after Segond’s fracture
(P = 0.08). The mean ATR at 30 of knee flexion was
20.7 ± 4.8 in the ACL intact condition, 26.9 ± 4.1 in
the ACL deficient knee (P[0.05) and 30.9 ± 3.8 after
Segond’s fracture (P = 0.005). Dynamic measurements
during the pivot-shift showed that the mean ATT was
7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the
ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the
ACL deficient knee with Segond’s fracture (P = 0.07).
The mean ATR was 9.6 ± 1.8 in the intact knee,
12.3 ± 2.3 in the ACL deficient knee (P[0.05) and
19.1 ± 3.1 in the ACL deficient knee with Segond’s
lesion (P = 0.016).
Conclusion An isolated lesion of the ACL only affects
ATT during static and dynamic measurements, while the
addition of Segond’s fracture has a significant effect on
ATR in both static and dynamic execution of the pivot-shift
test, as evaluated with the aid of navigation
The role of urban boundary layer investigated with high-resolution models and ground-based observations in Rome area: a step towards understanding parameterization potentialities
Abstract. The urban forcing on thermodynamical conditions can greatly influence the local evolution of the atmospheric boundary layer. Heat stored in an urban environment can produce noteworthy mesoscale perturbations of the lower atmosphere. The new generation of high-resolution numerical weather prediction models (NWP) is nowadays often applied also to urban areas. An accurate representation of cities is key role because of the cities' influence on wind, temperature and water vapor content of the planetary boundary layer (PBL). The Advanced Weather Research and Forecasting model WRF (ARW) has been used to reproduce the circulation in the urban area of Rome. A sensitivity study is performed using different PBL and surface schemes. The significant role of the surface forcing in the PBL evolution has been investigated by comparing model results with observations coming from many instruments (lidar, sodar, sonic anemometer and surface stations). The impact of different urban canopy models (UCMs) on the forecast has also been investigated. One meteorological event will be presented, chosen as statistically relevant for the area of interest. The WRF-ARW model shows a tendency to overestimate the vertical transport of horizontal momentum from upper levels to low atmosphere if strong large-scale forcing occurs. This overestimation is partially corrected by a local PBL scheme coupled with an advanced UCM. Moreover, a general underestimation of vertical motions has been verified
Higher Derivative CP(N) Model and Quantization of the Induced Chern-Simons Term
We consider higher derivative CP(N) model in 2+1 dimensions with the
Wess-Zumino-Witten term and the topological current density squared term. We
quantize the theory by using the auxiliary gauge field formulation in the path
integral method and prove that the extended model remains renormalizable in the
large N limit. We find that the Maxwell-Chern-Simons theory is dynamically
induced in the large N effective action at a nontrivial UV fixed point. The
quantization of the Chern-Simons term is also discussed.Comment: 8 pages, no figure, a minor change in abstract, added Comments on the
quantization of the Chern-Simons term whose coefficient is also corrected,
and some references are added. Some typos are corrected. Added a new
paragraph checking the equivalence between (3) and (5), and a related
referenc
Transport properties of molecular junctions from many-body perturbation theory
The conductance of single molecule junctions is calculated using a Landauer
approach combined to many-body perturbation theory MBPT) to account for
electron correlation. The mere correction of the density-functional theory
eigenvalues, which is the standard procedure for quasiparticle calculations
within MBPT, is found not to affect noticeably the zero-bias conductance. To
reduce it and so improve the agreement with the experiments, the wavefunctions
also need to be updated by including the non-diagonal elements of the
self-energy operator
Holographic aspects of three dimensional QCD from string theory
We study two aspects of 3D QCD with massless fermions in a holographic set-up
from string theory, based on D3/D7 branes; parity anomaly and baryons as baby
Skyrmions. We first give a novel account of parity anomaly of 3D QCD with odd
number of flavors from the IR holographic viewpoint by observing a subtle point
in D7 brane embeddings with a given fixed UV theory. We also discuss its UV
origin in terms of weakly coupled D-brane pictures. We then focus on the
parity-symmetric case of even number of N_F flavors, and study baryons in the
holographic model. We identify the monopoles of U(N_F) gauge theory dynamically
broken down to U(N_F/2)x U(N_F/2) in the holographic 4 dimensional bulk as a
holographic counter-part of 3D baby-Skyrmions for baryons in large N limit, and
work out some details how the mapping goes. In particular, we show that the
correct baryon charges emerge from the Witten effect with a space-varying theta
angle.Comment: 33 pages, 10 figures; v2: references added with comments, typos
corrected; v3: more references added; v4: holographic baryon profile and the
analysis of its baryon charge is significantly revised, correcting errors in
the previous discussio
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