191 research outputs found
Localizing merging black holes with sub-arcsecond precision using gravitational-wave lensing
The current gravitational-wave localization methods rely mainly on sources
with electromagnetic counterparts. Unfortunately, a binary black hole does not
emit light. Due to this, it is generally not possible to localize these objects
precisely. However, strongly lensed gravitational waves, which are forecasted
in this decade, could allow us to localize the binary by locating its lensed
host galaxy. Identifying the correct host galaxy is challenging because there
are hundreds to thousands of other lensed galaxies within the sky area spanned
by the gravitational-wave observation. However, we can constrain the lensing
galaxy's physical properties through both gravitational-wave and
electromagnetic observations. We show that these simultaneous constraints allow
one to localize quadruply lensed waves to one or at most a few galaxies with
the LIGO/Virgo/Kagra network in typical scenarios. Once we identify the host,
we can localize the binary to two sub-arcsec regions within the host galaxy.
Moreover, we demonstrate how to use the system to measure the Hubble constant
as a proof-of-principle application.Comment: 5 pages (main text) + 5 pages (methods+references), 5 figures.
Accepted to MNRA
A Complete Analysis for Pump Controlled Single Rod Actuators
In the current study a variable speed pump controlled hydrostatic circuit where an underlapped shuttle valve is utilized to compensate the unequal flow rate of a single rod actuator is analyzed. Parameters of the shuttle valve are included in the system analysis, rather than treating it as an ideal switching element as handled in literature. A linearized model of the system is obtained. An inverse kinematic model, which calculates the required pump drive speed for a desired actuator speed and given pilot pressure input, is formed. A numerical stability analysis program is developed, and the stability of all possible shuttle valve spool positons is determined. The theoretical findings are validated by non-linear simulation model responses
Seçmen tercihlerinin yönlendirilmesinde değer odaklı argümantasyon kullanımı
Manipulating voter preferences in favor of a certain political institution or opinion is performed by a lot of different techniques. However, in the process of voter persuasion, it is also a general necessity that the message produced by the political institution is designed in compliance with certain logical principles. Accordingly; politic argumentation on one hand, meets logical qualifications that a message should have, on the other hand, it offers certain technical structures and wording features. In parallel with that, in this study, the use of value-based argumentation in manipulating voter preferences is examined. Within this framework, "Referendum of Presidential Government System" conducted in 2017 is selected as the object of research. In the context of value-based argumentation, political argumentation analysis has been carried out on written material that AK Party and CHP produced within referendum campaign. As a result of the research, it is determined that three of totally seven AK Party arguments, two of totally nine CHP arguments produced for referendum topics are in harmony with the value-based argumentation style
Critical behavior of density of states near Fermi energy in low-dimensional disordered metals
We study the effect of electron-electron interaction on the one-particle
density of states (\emph{DOS}) of low-dimensional
disordered metals near Fermi energy within the framework of the finite
temperature conventional impurity diagram technique. We consider only diffusive
limit and by a geometric re-summation of the most singular first order
self-energy corrections via the Dyson equation we obtain a non-divergent
solution for the \emph{DOS} at low energies, while for higher energies the
well-known Altshuler-Aronov corrections are recovered. At the Fermi level
, this indicates that interacting disordered
two- and quasi-one-dimensional systems are in insulating state at zero
temperature. The obtained results are in good agreement with recent tunneling
experiments on two-dimensional GaAs/AlGaAs heterostructures and
quasi-one-dimensional doped multiwall carbon nanotubes.Comment: 8 pages, 4 figure
Low temperature regeneration of activated carbons using microwaves: Revising conventional wisdom
[EN] The purpose of this work was to explore the application of microwaves for the low temperature regeneration of activated carbons saturated with a pharmaceutical compound (promethazine). Contrary to expectations, microwave-assisted regeneration did not lead to better results than those obtained under conventional electric heating. At low temperatures the regeneration was incomplete either under microwave and conventional heating, being this attributed to the insufficient input energy. At mild temperatures, a fall in the adsorption capacity upon cycling was obtained in both devices, although this was much more pronounced for the microwave. These results contrast with previous studies on the benefits of microwaves for the regeneration of carbon materials. The fall in the adsorption capacity after regeneration was due to the thermal cracking of the adsorbed molecules inside the carbon porous network, although this effect applies to both devices. When microwaves are used, along with the thermal heating of the carbon bed, a fraction of the microwave energy seemed to be directly used in the decomposition of promethazine through the excitation of the molecular bonds by microwaves (microwave-lysis). These results point out that the nature of the adsorbate and its ability to interact with microwave are key factors that control the application of microwaves for regeneration of exhausted activated carbons.EÇ thanks The Council of Higher Education of Turkey (YÖK) for supporting her stay at INCAR (Oviedo) and the financial support of Istanbul University Research Fund (Project 3991) for her PhD thesis. JMB acknowledges CSIC for a JAE predoctoral fellowship. COA thanks the financial support of the projects CTM2008-01956 and CSIC-200980I131.Peer reviewe
X-ray enhancement and long-term evolution of swift J1822.3-1606
We investigate the X-ray enhancement and the long-term evolution of the recently discovered second "low-B magnetar" Swift J1822.3-1606 in the frame of the fallback disk model. During a soft gamma burst episode, the inner disk matter is pushed back to larger radii, forming a density gradient at the inner disk. Subsequent relaxation of the inner disk could account for the observed X-ray enhancement light curve of Swift J1822.3-1606. We obtain model fits to the X-ray data with basic disk parameters similar to those employed to explain the X-ray outburst light curves of other anomalous X-ray pulsars and soft gamma repeaters. The long period (8.4 s) of the neutron star can be reached by the effect of the disk torques in the long-term accretion phase ((1-3) x 10(5) yr). The currently ongoing X-ray enhancement could be due to a transient accretion epoch, or the source could still be in the accretion phase in quiescence. Considering these different possibilities, we determine the model curves that could represent the long-term rotational and the X-ray luminosity evolution of Swift J1822.3-1606, which constrain the strength of the magnetic dipole field to the range of (1-2) x 10(12) G on the surface of the neutron star
Threat vocalisations are acoustically similar between humans (Homo sapiens) and chimpanzees (Pan troglodytes)
In behavioural contexts like fighting, eating, and playing, acoustically distinctive vocalisations are produced across many mammalian species. Such expressions may be conserved in evolution, pointing to the possibility of acoustic regularities in the vocalisations of phylogenetically related species. Here, we test this hypothesis by comparing the degree of acoustic similarity between human and chimpanzee vocalisations produced in 10 similar behavioural contexts. We use two complementary analysis methods: Pairwise acoustic distance measures and acoustic separability metrics based on unsupervised learning algorithms. Cross-context analysis revealed that acoustic features of vocalisations produced when threatening another individual were distinct from other types of vocalisations and highly similar across species. Using a multimethod approach, these findings demonstrate that human vocalisations produced when threatening another person are acoustically similar to chimpanzee vocalisations in the same situation as compared to other types of vocalisations, likely reflecting a phylogenetically ancient vocal signalling system
The novel benzimidazole derivative BRP-7 inhibits leukotriene biosynthesis in vitro and in vivo by targeting 5-lipoxygenase-activating protein (FLAP).
BACKGROUND AND PURPOSE:
Leukotrienes (LTs) are inflammatory mediators produced via the 5-lipoxygenase (5-LOX) pathway and are linked to diverse disorders, including asthma, allergic rhinitis and cardiovascular diseases. We recently identified the benzimidazole derivative BRP-7 as chemotype for anti-LT agents by virtual screening targeting 5-LOX-activating protein (FLAP). Here, we aimed to reveal the in vitro and in vivo pharmacology of BRP-7 as an inhibitor of LT biosynthesis.
EXPERIMENTAL APPROACH:
We analysed LT formation and performed mechanistic studies in human neutrophils and monocytes, in human whole blood (HWB) and in cell-free assays. The effectiveness of BRP-7 in vivo was evaluated in rat carrageenan-induced pleurisy and mouse zymosan-induced peritonitis.
KEY RESULTS:
BRP-7 potently suppressed LT formation in neutrophils and monocytes and this was accompanied by impaired 5-LOX co-localization with FLAP. Neither the cellular viability nor the activity of 5-LOX in cell-free assays was affected by BRP-7, indicating that a functional FLAP is needed for BRP-7 to inhibit LTs, and FLAP bound to BRP-7 linked to a solid matrix. Compared with the FLAP inhibitor MK-886, BRP-7 did not significantly inhibit COX-1 or microsomal prostaglandin E2 synthase-1, implying the selectivity of BRP-7 for FLAP. Finally, BRP-7 was effective in HWB and impaired inflammation in vivo, in rat pleurisy and mouse peritonitis, along with reducing LT levels.
CONCLUSIONS AND IMPLICATIONS:
BRP-7 potently suppresses LT biosynthesis by interacting with FLAP and exhibits anti-inflammatory effectiveness in vivo, with promising potential for further development
BRP-187: A potent inhibitor of leukotriene biosynthesis that acts through impeding the dynamic 5-lipoxygenase/5-lipoxygenase-activating protein (FLAP) complex assembly
The pro-inflammatory leukotrienes (LTs) are formed from arachidonic acid (AA) in activated leukocytes, where 5-lipoxygenase (5-LO) translocates to the nuclear envelope to assemble a functional complex with the integral nuclear membrane protein 5-LO-activating protein (FLAP). FLAP, a MAPEG family member, facilitates AA transfer to 5-LO for efficient conversion, and LT biosynthesis critically depends on FLAP. Here we show that the novel LT biosynthesis inhibitor BRP-187 prevents the 5-LO/FLAP interaction at the nuclear envelope of human leukocytes without blocking 5-LO nuclear redistribution. BRP-187 inhibited 5-LO product formation in human monocytes and polymorphonuclear leukocytes stimulated by lipopolysaccharide plus N-formyl-methionyl-leucyl-phenylalanine (IC50=7-10nM), and upon activation by ionophore A23187 (IC50=10-60nM). Excess of exogenous AA markedly impaired the potency of BRP-187. Direct 5-LO inhibition in cell-free assays was evident only at >35-fold higher concentrations, which was reversible and not improved under reducing conditions. BRP-187 prevented A23187-induced 5-LO/FLAP complex assembly in leukocytes but failed to block 5-LO nuclear translocation, features that were shared with the FLAP inhibitor MK886. Whereas AA release, cyclooxygenases and related LOs were unaffected, BRP-187 also potently inhibited microsomal prostaglandin E2 synthase-1 (IC50=0.2μM), another MAPEG member. In vivo, BRP-187 (10mg/kg) exhibited significant effectiveness in zymosan-induced murine peritonitis, suppressing LT levels in peritoneal exudates as well as vascular permeability and neutrophil infiltration. Together, BRP-187 potently inhibits LT biosynthesis in vitro and in vivo, which seemingly is caused by preventing the 5-LO/FLAP complex assembly and warrants further preclinical evaluation
Optical identification and follow-up observations of SRGA J213151.5+491400 -- a new magnetic cataclysmic variable discovered with SRG Observatory
We report results of optical identification and multi-wavelength study of a
new polar-type magnetic cataclysmic variable (MCV), SRGA J213151.5+491400,
discovered by Spectrum Roentgen-Gamma () observatory in the course of the
all-sky survey. We present optical data from telescopes in Turkey (RTT-150 and
T100 at the T\"UBITAK National Observatory), and in Russia (6-m and 1-m at SAO
RAS), together with the X-ray data obtained with and
telescopes aboard and the observatory. We detect SRGA
J213151.5+491400 in a high state in 2020 (17.9 mag) that decreases about 3 mag
into a low state (21 mag) in 2021. We find only one significant period using
optical photometric time series analysis which reveals the white dwarf
spin/orbital period to be 0.059710(1) days (85.982 min). The long slit
spectroscopy in the high state yields a power law continuum increasing towards
the blue with a prominent He II line along with the Balmer line emissions with
no cyclotron humps; consistent with MCV nature. Doppler Tomography confirms the
polar nature revealing ballistic stream accretion along with magnetic stream
during the high state. These characteristics show that the new source is a
polar-type MCV. detections yield an X-ray flux of
(4.0-7.0)10 erg cm s in the high state.
detects a dominating hot plasma component (kT 21 keV in the
high state) declining to (4.0-6.0)10 erg cm s in
2021 (low state). The data obtained in the low state reveal a two-pole
accretor showing a soft X-ray component at (6-7) significance with a
blackbody temperature of 15-18 eV. A soft X-ray component has never been
detected for a polar in the low state before.Comment: 16 pages, 4 Tables and 15 Figures. Accepted for publication in A&A as
it stand
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