411 research outputs found
VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift
In this work we present new APEX/SEPIA Band-5 observations targeting the CO
() emission line of 24 Herschel-detected galaxies at .
Combining this sample {with} our recent new Valpara\'iso ALMA Line Emission
Survey (VALES), we investigate the star formation efficiencies (SFEs =
SFR/) of galaxies at low redshift. We find the SFE of our sample
bridges the gap between normal star-forming galaxies and Ultra-Luminous
Infrared Galaxies (ULIRGs), which are thought to be triggered by different star
formation modes. Considering the as the SFR and the
ratio, our data show a continuous and smooth increment as a function of
infrared luminosity (or star formation rate) with a scatter about 0.5 dex,
instead of a steep jump with a bimodal behaviour. This result is due to the use
of a sample with a much larger range of sSFR/sSFR using LIRGs, with
luminosities covering the range between normal and ULIRGs. We conclude that the
main parameters controlling the scatter of the SFE in star-forming galaxies are
the systematic uncertainty of the conversion factor, the gas
fraction and physical size.Comment: 9pages, 7 figures, 1 table, accepted for publication in MNRA
A functionally specialized population of mucosal CD103+ DCs induces Foxp3+ regulatory T cells via a TGF-β– and retinoic acid–dependent mechanism
Foxp3+ regulatory T (T reg) cells play a key role in controlling immune pathological re actions. Many develop their regulatory activity in the thymus, but there is also evidence for development of Foxp3+ T reg cells from naive precursors in the periphery. Recent studies have shown that transforming growth factor (TGF)-β can promote T reg cell development in culture, but little is known about the cellular and molecular mechanisms that mediate this pathway under more physiological conditions. Here, we show that after antigen activation in the intestine, naive T cells acquire expression of Foxp3. Moreover, we identify a population of CD103+ mesenteric lymph node dendritic cells (DCs) that induce the devel opment of Foxp3+ T reg cells. Importantly, promotion of T reg cell responses by CD103+ DCs is dependent on TGF-β and the dietary metabolite, retinoic acid (RA). These results newly identify RA as a cofactor in T reg cell generation, providing a mechanism via which functionally specialized gut-associated lymphoid tissue DCs can extend the repertoire of T reg cells focused on the intestine
Shock Wave Structure in a Strongly Nonlinear Granular Lattice with Viscous Dissipation
The shock wave structure in a one-dimensional lattice (e.g. granular chain)
with a power law dependence of force on displacement between particles with
viscous dissipation is considered and compared to the corresponding long wave
approximation. A dissipative term depending on the relative velocity between
neighboring particles is included in the discrete model to investigate its
influence on the shape of steady shock profiles. The critical viscosity
coefficient is obtained from the long-wave approximation for arbitrary values
of the exponent n and denotes the transition from an oscillatory to a monotonic
shock profile in stronly nonlinear systems. The expression for the critical
viscosity coefficient converges to the known equation for the critical
viscosity in the weakly nonlinear case. Values of viscosity based on this
expression are comparable to the values obtained in the numerical analysis of a
discrete particle lattice with a Herzian contact interaction corresponding to n
= 3/2. An initial disturbance in a discrete system approaches a stationary
shock profile after traveling a short distance that is comparable to the width
of the leading pulse of a stationary shock front. The shock front width is
minimized when the viscosity is equal to its critical value.Comment: 20 pages, 6 figure
The evolution of Balmer jump selected galaxies in the ALHAMBRA survey
We present a new color-selection technique, based on the Bruzual & Charlot
models convolved with the bands of the ALHAMBRA survey, and the redshifted
position of the Balmer jump to select star-forming galaxies in the redshift
range 0.5 < z < 1.5. These galaxies are dubbed Balmer jump Galaxies BJGs. We
apply the iSEDfit Bayesian approach to fit each detailed SED and determine
star-formation rate (SFR), stellar mass, age and absolute magnitudes. The mass
of the haloes where these samples reside are found via a clustering analysis.
Five volume-limited BJG sub-samples with different mean redshifts are found to
reside in haloes of median masses slightly
increasing toward z=0.5. This increment is similar to numerical simulations
results which suggests that we are tracing the evolution of an evolving
population of haloes as they grow to reach a mass of at z=0.5. The likely progenitors of our samples at z3 are Lyman
Break Galaxies, which at z2 would evolve into star-forming BzK galaxies,
and their descendants in the local Universe are elliptical galaxies.Hence, this
allows us to follow the putative evolution of the SFR, stellar mass and age of
these galaxies. From z1.0 to z0.5, the stellar mass of the volume
limited BJG samples nearly does not change with redshift, suggesting that major
mergers play a minor role on the evolution of these galaxies. The SFR evolution
accounts for the small variations of stellar mass, suggesting that star
formation and possible minor mergers are the main channels of mass assembly.Comment: 14 pages, 10 figures. Submitted to A&A. It includes first referee's
comments. Abstract abridged due to arXiv requirement
Cyrhetrenylaniline and new organometallic phenylimines derived from 4- and 5-nitrothiophene: Synthesis, characterization, X-Ray structures, electrochemistry and in vitro anti-T. brucei activity
A novel series of cyrhetrenyl (3a-4a) and ferrocenyl (3b-4b) Schiff bases were synthesized through a condensation reaction, between the known 4-ferrocenylaniline (2b) or the unreported 4-cyhretrenylaniline (2a) with 4- or 5-nitrothiophenecarboxaldehyde. The structure of 2a and the new Schiff bases have been elucidated using conventional spectroscopic techniques (FT-IR, 1H and 13C NMR), mass spectrometry, and single-crystal X-ray diffraction analysis of compounds 2a, 4a and 3b. Cyclic voltammetry of organometallic phenylimines derived from 5-nitrothiophene showed NO2 group reduction potentials (E1/2z 0.575 V) that were more anodic than those registered for their 4-nitro analogues (E1/2z 0.981 V). All organometallic imines were tested against the bloodstream form of Trypanosoma brucei. Evaluation indicated that the most active complexes are the 5-nitrothiophene derivatives, 4a, which were remarkably more active than nifurtimox. In addition, complex 4b resulted in less toxicity to host L6 cells than nifurtimox. The results revealed that the electronic effects of cyrhetrene and ferrocene are not an influential factor in E1/2 and anti-Trypanosoma brucei activity for these new imines, which is probably due to the non-coplanarity of the [(h5-C5H4)-C6H4-N=CH-(C4H2S)] system
Elemental abundances differences in the massive planet-hosting wide binary HD 196067-68
It has been suggested that small chemical anomalies observed in
planet-hosting wide binary systems could be due to planet signatures, where the
role of the planetary mass is still unknown. We search for a possible planet
signature by analyzing the Tc trends in the remarkable binary system
HD196067-HD196068. At the moment, only HD196067 is known to host a planet which
is near the brown dwarf regime. We take advantage of the strong physical
similarity between both stars, which is crucial to achieving the highest
possible precision in stellar parameters and elemental chemical abundances.
This system gives us a unique opportunity to explore if a possible depletion of
refractories in a binary system could be inhibited by the presence of a massive
planet. We performed a line-by-line chemical differential study, employing the
non-solar-scaled opacities, in order to reach the highest precision in the
calculations. After differentially comparing both stars, HD196067 displays a
clear deficiency in refractory elements in the Tc plane, a lower iron content
(0.051 dex) and also a lower Li I content (0.14 dex) than its companion. In
addition, the differential abundances reveal a Tc trend. These targets
represent the first cases of an abundance difference around a binary system
hosting a super-Jupiter. Although we explored several scenarios to explain the
chemical anomalies, none of them can be entirely ruled out. Additional
monitoring of the system as well as studies of larger sample of wide binary
systems hosting massive planets, are needed to better understand the chemical
abundance trend observed in HD196067-68.Comment: 9 pages, six figures, three table
Tunneling dynamics in exactly-solvable models with triple-well potentials
Inspired by new trends in atomtronics, cold atoms devices and Bose-Einstein
condensate dynamics, we apply a general technique of N=4 extended
Supersymmetric Quantum Mechanics to isospectral Hamiltonians with triple-well
potentials, i.e. symmetric and asymmetric. Expressions of quantum-mechanical
propagators, which take into account all states of the spectrum, are obtained,
within the N = 4 SQM approach, in the closed form. For the initial Hamiltonian
of a harmonic oscillator, we obtain the explicit expressions of potentials,
wavefunctions and propagators. The obtained results are applied to tunneling
dynamics of localized states in triple-well potentials and for studying its
features. In particular, we observe a Josephson-type tunneling transition of a
wave packet, the effect of its partial trapping and a non-monotonic dependence
of tunneling dynamics on the shape of a three-well potential. We investigate,
among others, the possibility of controlling tunneling transport by changing
parameters of the central well, and we briefly discuss potential applications
of this aspect to atomtronic devices.Comment: Latex, 28 pages, 7 Figs, 2 Tables; minor presentation changes,
journal versio
Multiwavelength monitoring of the nucleus in PBC J2333.9-2343: the giant radio galaxy with a blazar-like core
PBC J2333.9-2343 is a giant radio galaxy at z = 0.047 with a bright central
core associated to a blazar nucleus. If the nuclear blazar jet is a new phase
of the jet activity, then the small orientation angle suggest a dramatic change
of the jet direction. We present observations obtained between September 2018
and January 2019 (cadence larger than three days) with Effeslberg, SMARTS-1.3m,
ZTF, ATLAS, Swift, and Fermi-LAT, and between April-July 2019 (daily cadence)
with SMARTS-1.3m and ATLAS. Large (>2x) flux increases are observed on
timescales shorter than a month, which are interpreted as flaring events. The
cross correlation between the SMARTS-1.3m monitoring in the NIR and optical
shows that these data do not show significant time lag within the measured
errors. A comparison of the optical variability properties between non-blazars
and blazars AGN shows that PBC J2333.9-2343 has properties more comparable to
the latter. The SED of the nucleus shows two peaks, that were fitted with a one
zone leptonic model. Our data and modelling shows that the high energy peak is
dominated by External Compton from the dusty torus with mild contribution from
Inverse Compton from the jet. The derived jet angle of 3 degrees is also
typical of a blazar. Therefore, we confirm the presence of a blazar-like core
in the center of this giant radio galaxy, likely a Flat Spectrum Radio Quasar
with peculiar properties.Comment: Accepted for publication in MNRAS. 15 pages, 6 figures, 2 appendix
including tables and figure
Microglial ramification, surveillance and interleukin-1beta release are regulated by the two-pore domain K+ channel THIK-1
Microglia exhibit two modes of motility: they constantly extend and retract their processes to survey the brain, but they also send out targeted processes to envelop sites of tissue damage. We now show that these motility modes differ mechanistically. We identify the two-pore domain channel THIK-1 as the main K+ channel expressed in microglia in situ. THIK-1 is tonically active, and its activity is potentiated by P2Y12 receptors. Inhibiting THIK-1 function pharmacologically or by gene knockout depolarizes microglia, which decreases microglial ramification and thus reduces surveillance, whereas blocking P2Y12 receptors does not affect membrane potential, ramification, or surveillance. In contrast, process outgrowth to damaged tissue requires P2Y12 receptor activation but is unaffected by blocking THIK-1. Block of THIK-1 function also inhibits release of the pro-inflammatory cytokine interleukin-1β from activated microglia, consistent with K+ loss being needed for inflammasome assembly. Thus, microglial immune surveillance and cytokine release require THIK-1 channel activity
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