480 research outputs found
Anomalous Raman scattering from phonons and electrons of superconducting FeSe
We report interesting anomalies in the temperature dependent Raman spectra of
FeSe measured from 3K to 300K in the spectral range from 60 to 1800
cm and determine their origin using complementary first-principles
density functional calculations. A phonon mode near 100 cm exhibits a
sharp increase by 5% in frequency below a temperature T ( 100
K) attributed to strong spin-phonon coupling and onset of short-range
antiferromagnetic order. In addition, two high frequency modes are observed at
1350 cm and 1600 cm, attributed to electronic Raman scattering
from ()to / -orbitals of Fe.Comment: 19 pages, 4 figures, 1 tabl
Disaster financing and poverty traps for poor households: Realities in Northern India
This paper addresses household-level disaster financing strategies of the poor in developing countries within the context of current poverty trap discussions. It presents findings on risk perceptions and loss financing practices in relation to floods and droughts in Uttar Pradesh, India. The study found that, due to financial shocks, the risk of households falling below the subsistence level and into a poverty trap is high. In this context, the paper links current approaches in household welfare-drive disaster risk financing to the survey results and provides policy recommendations
The Structure of the Literary Problem in the Formation of the Local Text Substrate
The article aims to study the structure of the literary problem in the formation of
the local text substrate. The study uses the methodology of studying the language
when it changes in time and space. The article explains the basics of the
methodological support of the translation complex and the structure of its
application in private studies of foreign cultures and communicants. The results
of the study showed the possibility of interaction between the subjects of
linguistic exchange and the dynamics of the translation and literary component.
The novelty of the study is determined by the fact that the work defines methods
that can be used not only by local researchers but also by foreign-speaking
communicants. The research results can be used in practical activities to bridge
the gap between understanding the local text in translation studies and its
structuring in the local versions of individual authors
Vacuum Induced Coherences in Radiatively Coupled Multilevel Systems
We show that radiative coupling between two multilevel atoms having
near-degenerate states can produce new interference effects in spontaneous
emission. We explicitly demonstrate this possibility by considering two
identical V systems each having a pair of transition dipole matrix elements
which are orthogonal to each other. We discuss in detail the origin of the new
interference terms and their consequences. Such terms lead to the evolution of
certain coherences and excitations which would not occur otherwise. The special
choice of the orientation of the transition dipole matrix elements enables us
to illustrate the significance of vacuum induced coherence in multi-atom
multilevel systems. These coherences can be significant in energy transfer
studies.Comment: 13 pages including 8 figures in Revtex; submitted to PR
PKS 0537-441: extended [O II] emission and a binary QSO?
We present high-resolution imaging and low-resolution spectroscopy of the BL
Lac object PKS 0537-441 (z = 0.893) and its environment. The observations were
designed to clarify, whether the properties of PKS 0537-441 are affected by
gravitational microlensing, or whether PKS 0537-441 and its environment act as
a lensing system itself. Our observations show that neither case seems to be
likely. We did not find a galaxy along the line-of-sight to the BL Lac as
claimed previously, our spectroscopy shows that none of the four closest
companion galaxies is at high redshift. Two of the four nearby companion
galaxies to PKS 0537-441 are within 200 km/s of the systemic velocity of the BL
Lac (z = 0.892 and 0.895, respectively). The third companion galaxy is at
higher redshift (z = 0.947). The fourth companion galaxy shows evidence of Mg
II absorption redwards of its systemic velocity and is perhaps a mini low
ionization BAL QSO at z = 0.885. If the latter can be confirmed, PKS 0537-441
is the first BL Lacertae object being a member of a binary Quasar. We also
detected extended [O II] emission in the off-nuclear spectrum of PKS 05371-441,
which is most likely due to photoionization from the active nucleus.
Alternatively, the extended [O II] emission is due to jet-cloud interaction
with the counterjet of PKS 0537-441. Our clustering analysis indicates that PKS
0537-441 is located in a cluster environment as rich as Abell type 0-1. This is
supported by the detection of four galaxies in the field with similar redshifts
as the BL Lac (Delta z < 0.002). We found serendipitously even more galaxies at
somewhat higher redshifts (z = 0.9-1). Thus, PKS0537-441 might be located in
front of a galaxy cluster at somewhat higher redshift or even be part of a
large-scale structure with an extension towards the BL Lac.Comment: 13 pages, 9 figures, accepted for publication in A&
The Nature of Composite LINER/HII Galaxies, As Revealed from High-Resolution VLA Observations
A sample of 37 nearby galaxies displaying composite LINER/HII and pure HII
spectra was observed with the VLA in an investigation of the nature of their
weak radio emission. The resulting radio contour maps overlaid on optical
galaxy images are presented here, together with an extensive literature list
and discussion of the individual galaxies. Radio morphological data permit
assessment of the ``classical AGN'' contribution to the global activity
observed in these ``transition'' LINER galaxies. One in five of the latter
objects display clear AGN characteristics: these occur exclusively in
bulge-dominated hosts.Comment: 31 pages, 27 figures, accepted by ApJ
Growth, structure analysis and anisotropic superconducting properties of MgB2 single crystals
Here we report the growth of sub-millimeter MgB2 single crystals of various
shapes under high pressure in Mg-B-N system. Structure refinement using a
single-crystal X-ray diffraction analysis gives lattice parameters a=3.0851(5)
A and c=3.5201(5) A with small reliability factors (Rw =0.025, R=0.018), which
enables us to analyze the Fourier and Fourier difference maps. The maps clearly
show the B sp2 orbitals and covalency of the B-B bonds. The sharp
superconducting transitions at Tc =38.1-38.3K were obtained in both
magnetization (DTc =0.6K) and resistivity (DTc <0.3K) measurements. Resistivity
measurements with magnetic fields applied parallel and perpendicular to the Mg
and B sheets reveal the anisotropic nature of this compound, with upper
critical field anisotropy ratio of about 2.7.Comment: 9 pages, 5 figures and 1 tabl
Super-conducting critical fields and anisotropy of a MgB2 single crystal
Despite the intense activity in the year since the discovery of
superconductivity in MgB2, key parameters, in particular the upper and lower
critical fields Hc2 and Hc1 and their anisotropies, are not well-established,
largely because of the difficulty of growing MgB2 crystals. Attempts have been
made to deduce these parameters from experiments on polycrystalline material,
but they have substantial uncertainties. Hc2 is particularly important for
applications, as it is the field which quenches bulk super-conductivity. In
terms of understanding MgB2, it is now clear that the conventional
electron-phonon interaction is strong enough to account for the high transition
temperature Tc, but the consequences of the double super-conducting gap for the
anisotropy and its dependence on temperature, are uncertain. Here we describe
detailed direct measurements of Hc1(T) and Hc2(T) for the two principal
crystallographic directions in a clean single crystal of MgB2. For fields in
the c-direction, = and
is ; this ratio of critical fields is rather low and implies that
MgB2 is only just a Type II super-conductor. The anisotropies of both critical
fields are close to 2.Comment: 3 pages 3 figure
Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
Quasiclassic Uzadel equations for two-band superconductors in the dirty limit
with the account of both intraband and interband scattering by nonmagnetic
impurities are derived for any anisotropic Fermi surface. From these equations
the Ginzburg-Landau equations, and the critical temperature are obtained.
An equation for the upper critical field, which determines both the temperature
dependence of and the orientational dependence of
as a function of the angle between and the c-axis is
obtained. It is shown that the shape of the curve essentially
depends on the ratio of the intraband electron diffusivities and ,
and can be very different from the standard one-gap dirty limit theory. In
particular, the value can considerably exceed ,
which can have important consequences for applications of . A scaling
relation is proposed which enables one to obtain the angular dependence of
from the equation for at . It is shown
that, depending on the relation between and , the ratio of the upper
critical field for and can both increase and decrease as the temperature decreases. Implications
of the obtained results for are discussed
Prognostic Role of Gene Mutations in Chronic Myelomonocytic Leukemia Patients Treated With Hypomethylating Agents
Somatic mutations contribute to the heterogeneous prognosis of chronic myelomonocytic leukemia (CMML). Hypomethylating agents (HMAs) are active in CMML, but analyses of small series failed to identify mutations predicting response or survival. We analyzed a retrospective multi-center cohort of 174 CMML patients treated with a median of 7 cycles of azacitidine (n = 68) or decitabine (n = 106). Sequencing data before treatment initiation were available for all patients, from Sanger (n = 68) or next generation (n = 106) sequencing. Overall response rate (ORR) was 52%, including complete response (CR) in 28 patients (17%). In multivariate analysis, ASXL1 mutations predicted a lower ORR (Odds Ratio [OR] = 0.85, p = 0.037), whereas TET2mut/ASXL1wt genotype predicted a higher CR rate (OR = 1.18, p = 0.011) independently of clinical parameters. With a median follow-up of 36.7 months, overall survival (OS) was 23.0 months. In multivariate analysis, RUNX1mut (Hazard Ratio [HR] = 2.00, p = .011), CBLmut (HR = 1.90, p = 0.03) genotypes and higher WBC (log10(WBC) HR = 2.30, p = .005) independently predicted worse OS while the TET2mut/ASXL1wt predicted better OS (HR = 0.60, p = 0.05). CMML-specific scores CPSS and GFM had limited predictive power. Our results stress the need for robust biomarkers of HMA activity in CMML and for novel treatment strategies in patients with myeloproliferative features and RUNX1 mutations. Keywords: Chronic myelomonocytic leukemia, Hypomethylating agents, Somatic mutations, Prognosi
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