118 research outputs found
Long range order for lattice dipoles
We consider a system of classical Heisenberg spins on a cubic lattice in
dimensions three or more, interacting via the dipole-dipole interaction. We
prove that at low enough temperature the system displays orientational long
range order, as expected by spin wave theory. The proof is based on reflection
positivity methods. In particular, we demonstrate a previously unproven
conjecture on the dispersion relation of the spin waves, first proposed by
Froehlich and Spencer, which allows one to apply infrared bounds for estimating
the long distance behavior of the spin-spin correlation functions.Comment: 9 page
Pattern densities in fluid dimer models
In this paper, we introduce a family of observables for the dimer model on a
bi-periodic bipartite planar graph, called pattern density fields. We study the
scaling limit of these objects for liquid and gaseous Gibbs measures of the
dimer model, and prove that they converge to a linear combination of a
derivative of the Gaussian massless free field and an independent white noise.Comment: 38 pages, 3 figure
Multiwavelength study of extreme variability in LEDA 1154204: A changing-look event in a type 1.9 Seyfert
Context. Multiwavelength studies of transients in actively accreting
supermassive black holes have revealed that large-amplitude variability is
frequently linked to significant changes in the optical spectra -- a phenomenon
referred to as changing-look AGN (CLAGN).
Aim. In 2020, the Zwicky Transient Facility detected a transient flaring
event in the type-1.9 AGN 6dFGS~gJ042838.8-000040, wherein a sharp increase in
magnitude of 0.55 and 0.3 in the - and -bands, respectively,
occurred over 40 days. Spectrum Roentgen Gamma (SRG)/eROSITA also
observed the object in X-rays as part of its all-sky survey, but only after the
flare had started decaying.
Methods. We performed a three-year, multiwavelength follow-up campaign of the
source to track its spectral and temporal characteristics. This campaign
included multiple ground-based facilities for optical spectroscopic monitoring
and space-based observatories including \textit{XMM-Newton} and \textit{Swift}
for X-ray and UV observations.
Results. An optical spectrum taken immediately after the peak revealed a
changing-look event wherein the source had transitioned from type 1.9 to 1,
with the appearance of a double-peaked broad H line and a blue
continuum, both absent in an archival spectrum from 2005. The X-ray emission
exhibits dramatic flux variation: a factor of 17, but with no spectral
evolution, as the power-law photon index remained 1.9. There is no
evidence of a soft X-ray excess. Overall the object exhibits no apparent
signatures of a tidal disruption event.
Conclusions. The transient event was likely triggered by a disk instability
in a pre-existing accretion flow, culminating in the observed multi-wavelength
variability and CLAGN event.Comment: 34 pages, 24 figures, Submitted to Astronomy & Astrophysic
Binderless zeolite monoliths production with sacrificial biopolymers
3D printing has emerged as an attractive way of formulating structured adsorbents, as it imparts lower manufacturing costs compared to hydraulic extrusion while also allowing for unprecedented geometric control. However, binderless structures have not been fabricated by 3D printing, as ink formulation has previously required clay binders which cannot be easily removed. In this study, we report the development of a facile approach to shape engineer binderless zeolites. 3D-printed inks comprised of 13X, 5A, ZSM-5, and experimental South African zeolites were prepared using gelatin and pectin as binding agents along with dropwise addition of various solvents. After printing, the dried monoliths were calcined to remove the biopolymers and form 100% pure zeolite structures. From N2 physisorption and CO2 adsorption measurements at 0 °C, all monoliths showed narrowing below 1 nm from their powders, which was attributed to pore malformation caused by intraparticle bridging during calcination
Wavelength-resolved Reverberation Mapping of quasar CTSC30.10: Dissecting MgII and FeII emission regions
We present the results of the reverberation monitoring aimed at MgII broad
line and FeII pseudocontinuum for the luminous quasar CTS C30.10 (z = 0.90052)
with the Southern African Large Telescope covering the years 2012-2021. We
aimed at disentangling the MgII and UV FeII variability and the first
measurement of UV FeII time delay for a distant quasar. We used several methods
for time-delay measurements and determined both FeII and MgII time delays as
well as performed a wavelength-resolved time delay study for a combination of
MgII and FeII in the 2700 - 2900 \AA restframe wavelength range. We obtain the
time delay for MgII of days in the rest frame, while
for FeII we have two possible solutions of days and
in the rest frame. Combining this result with the old
measurement of FeII UV time delay for NGC 5548 we discuss for the first time
the radius-luminosity relation for UV FeII with the slope consistent with
within uncertainties. Since FeII time delay has a shorter time-delay component
but lines are narrower than MgII, we propose that the line delay measurement is
biased towards the BLR part facing the observer, with the bulk of the Fe II
emission may arise from the more distant BLR region, one that is shielded from
the observer.Comment: 22 pages, 19 Figures, 6 Tables, Submitted to Astronomy and
Astrophysics, Comments are welcom
Wavelength-resolved reverberation mapping of intermediate redshift quasars HE 0413-4031 and HE 0435-4312: Dissecting Mg II, optical Fe II, and UV Fe II emission regions
We present the wavelength-resolved reverberation mapping (RM) of combined
MgII and UV FeII broad-line emissions for two intermediate redshifts
(z1), luminous quasars - HE 0413-4031 and HE 0435-4312, monitored by the
SALT and 1-m class telescopes between 2012-2022. Through this technique, we aim
to disentangle the Mg II and FeII emission regions and to build a
radius-luminosity relation for UV FeII emission, which has so far remained
unconstrained. Several methodologies have been applied to constrain the time
delays for total MgII and FeII emissions. In addition, this technique is
performed to quantify the inflow or outflow of broad-line region gas around the
supermassive black hole and to disentangle the emission/emitting regions from
lines produced in proximity to each other. The mean total FeII time delay is
nearly equal to the mean total Mg II time delay for HE 0435-4312 suggesting a
co-spatiality of their emissions. However, in HE 0413-4031, the mean FeII time
delay is found to be longer than the mean MgII time delay, suggesting that FeII
is produced at longer distances from the black hole. The UV Fe II R-L relation
is updated with these two quasars and compared with the optical FeII relation,
which suggests that the optical FeII region is located further than the UV FeII
by a factor of 1.7-1.9 i.e. . We
detected a weak pattern in the time delay vs. wavelength relation, suggesting
that the MgII broad-line originates a bit closer to the SMBH than the UV FeII,
however, the difference is not very significant. Comparison of MgII, UV, and
optical FeII R-L relations suggests that the difference may be larger for
lower-luminosity sources, possibly with the MgII emission originating further
from the SMBH. In the future, more RM data will be acquired to put better
constraints on these trends, in particular the UV FeII R-L relation.Comment: 24 pages, 16 figures, 5 tables, Accepted for publication in A&A, in
Pres
Current status of clinical outcome measures in inclusion body myositis: a systematised review
OBJECTIVES: Sporadic inclusion body myositis (IBM) is a debilitating idiopathic inflammatory myopathy (IIM) which affects hand function, ambulation, and swallowing. There is no approved pharmacological therapy for IBM, and there is a lack of suitable outcome measure to assess the effect of an intervention. The IBM scientific interest group under IMACS reviewed the previously used outcome measures in IBM clinical studies to lay the path for developing a core set of outcome measures in IBM. METHODS: In this systematised review, we have extracted all outcome measures reported in IBM clinical studies to determine what measures were being used and to assess the need for optimising outcome measures in IBM. RESULTS: We found 13 observational studies, 17 open-label clinical trials, and 15 randomised control trials (RCTs) in IBM. Six-minute walk distance, IBM-functional rating scale (IBM-FRS), quantitative muscle testing, manual muscle testing, maximal voluntary isometric contraction testing, and thigh muscle volume measured by MRI were used as primary outcome measures. Twelve different outcome measures of motor function were used in IBM clinical trials. IBM-FRS was the most used measure of functionality. Swallowing function was reported as a secondary outcome measure in only 3 RCTs. CONCLUSIONS: There are inconsistencies in using outcome measures in clinical studies in IBM. The core set measures developed by the IMACS group for other IIMs are not directly applicable to IBM. As a result, there is an unmet need for an IBM-specific core set of measures to facilitate the evaluation of new potential therapeutics for IBM
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