296 research outputs found
Intense green-yellow electroluminescence from Tb+-implanted silicon-rich silicon nitride/oxide light emitting devices
High optical power density of 0.5 mW/cm2, external quantum efficiency of 0.1%, and population inversion of 7% are reported from Tb+-implanted silicon-rich silicon nitride/oxide light emitting devices. Electrical and electroluminescence mechanisms in these devices were investigated. The excitation cross section for the 543ânm Tb3+ emission was estimated under electrical pumping, resulting in a value of 8.2âĂâ10â14 cm2, which is one order of magnitude larger than one reported for Tb3+:SiO2 light emitting devices. These results demonstrate the potentiality of Tb+-implanted silicon nitride material for the development of integrated light sources compatible with Si technology
A catalogue of ULX coincidences with FIRST radio sources
We search for ultra luminous X-ray source (ULXs) radio counterparts located
in nearby galaxies in order to constrain their physical nature. Our work is
based on a systematic cross-identification of the most recent and extensive
available ULX catalogues and archival radio data. A catalogue of 70 positional
coincidences is reported. Most of them are located within the galaxy nucleus.
Among them, we find 11 new cases of non-nuclear ULX sources with possibly
associated radio emission.Comment: Accepted for publication in A&A; 17 pages, 9 figure
Bean rust resistance and yield of black bean genotypes under field conditions
Objective: To identify black bean lines resistant to rust under field conditions, and with yield equal to or greater than that of three varieties for commercial use in Veracruz. Design/methodology/approach: The genotypes were evaluated in a randomized block experimental design with three replications. Its reaction to rust was rated on an incidence scale of 1 to 9 and grain yield was estimated in kilograms per hectare. Analyses of variance were performed and to separate averages, the Least Significant Difference was applied at 0.05. Correlation analyses were also carried out between the rust incidence values ââand the yield of the genotypes at each evaluation site. Results: Nine lines were resistant to rust with an average incidence of between 1.78 and 3.33, of which Jamapa Plus/XRAV-187-3-4-4 was the most productive with an average yield of 2183.4 kg ha-1, statistically similar. to that obtained by the Jamapa Plus/XRAV-187-3-4-1 and Jamapa Plus/XRAV-187-3-1-2 lines and the VerdĂn variety, and significantly higher than that of the rest of the genotypes. Limitations on study/implications: Although the rust occurred in the three study locations, its degree of incidence and the stage in which it appeared were different. However, in all cases, the degree of infection was sufficient to evaluate the reaction of the genotypes to this disease. Findings/conclusions: Three lines resistant to rust were identified under field conditions, with an average yield significantly higher than that of the Negro Jamapa and Negro MedellĂn varieties.
Objective: To identify black beans lines resistant to bean rust under field conditions, which have similar or higher yield than three commercial varieties sown in Veracruz, Mexico.
Design/Methodology/Approach: The genotypes were evaluated using a completely randomized block design. The reaction of the genotypes to bean rust was qualified using a 1-9 incidence rate, while grain yield was estimated in kg ha-1. An analysis of variance was carried out and the resulting means were divided using a 0.05 Least Significant Difference (LSD). Additionally, a correlation analysis between the incidence values of bean rust and the yield of the genotypes was carried out in each evaluation site.
Results: Nine lines were resistant to bean rust (incidence average: 1.78-3.33). Out of these lines, Jamapa Plus/XRAV-187-3-4-4 was the most productive line, with a 2,183.4 kg ha-1 average yield. This result is statistically similar to the results of the Jamapa Plus/XRAV-187-3-4-1 and Jamapa Plus/XRAV-187-3-1-2 lines and the VerdĂn variety. In addition, the results of Jamapa Plus/XRAV-187-3-4-4 are slightly higher than the results obtained by the rest of the genotypes.
Study Limitations/Implications: Although bean rust was recorded in three of the localities of the study area, the incidence degree and the stage when it was found were different. However, in all the cases, the infection degree was enough to evaluate the reactions of the genotypes to this disease.
Findings/Conclusions: Three bean rust-resistant lines were identified under field conditions. They had a significantly higher average yield than the Negro Jamapa and Negro MedellĂn varieties
A new L-dwarf member of the moderately metal-poor triple system HD 221356
We report on the discovery of a fourth component in the HD 221356 star
system, previously known to be formed by an F8V, slightly metal-poor primary
([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion
search based on VISTA Hemisphere Survey (VHS) and 2MASS catalogues, we have
detected a faint (J=13.76+/-0.04 mag) co-moving companion of the F8 star
located at angular separation of 12.13+/-0.18 arcsec (position angle of
221.8+/-1.7), corresponding to a projected distance of ~312 AU at 26 pc.
Near-infrared spectroscopy of the new companion, covering the 1.5-2.4 micron
wavelength range with a resolving power of R~600, indicates an L1+/-1 spectral
type. Using evolutionary models the mass of the new companion is estimated at
~0.08 solar masses, which places the object close to the stellar-substellar
borderline. This multiple system provides an interesting example of objects
with masses slightly above and below the hydrogen burning mass limit. The low
mass companions of HD 221356 have slightly bluer colours than field dwarfs with
similar spectral type, which is likely a consequence of the sub-solar
metallicity of the system.Comment: 7 pages, 4 figures, accepted for publication in MNRA
Activating Transcription Factor 4 Modulates TGFÎČ-Induced Aggressiveness in Triple-Negative Breast Cancer via SMAD2/3/4 and mTORC2 Signaling
Purpose: On the basis of the identified stress-independent cellular functions of activating transcription factor 4 (ATF4), we reported enhanced ATF4 levels in MCF10A cells treated with TGFÎČ1. ATF4 is overexpressed in patients with triple-negative breast cancer (TNBC), but its impact on patient survival and the underlying mechanisms remain unknown. We aimed to determine ATF4 effects on patients with breast cancer survival and TNBC aggressiveness, and the relationships between TGFÎČ and ATF4. Defining the signaling pathways may help us identify a cell signaling-tailored gene signature.Experimental Design: Patient survival data were determined by Kaplan-Meier analysis. Relationship between TGFÎČ and ATF4, their effects on aggressiveness (tumor proliferation, metastasis, and stemness), and the underlying pathways were analyzed in three TNBC cell lines and in vivo using patient-derived xenografts (PDX).Results: ATF4 overexpression correlated with TNBC patient survival decrease and a SMAD-dependent crosstalk between ATF4 and TGFÎČ was identified. ATF4 expression inhibition reduced migration, invasiveness, mammosphere-forming efficiency, proliferation, epithelial-mesenchymal transition, and antiapoptotic and stemness marker levels. In PDX models, ATF4 silencing decreased metastases, tumor growth, and relapse after chemotherapy. ATF4 was shown to be active downstream of SMAD2/3/4 and mTORC2, regulating TGFÎČ/SMAD and mTOR/RAC1-RHOA pathways independently of stress. We defined an eight-gene signature with prognostic potential, altered in 45% of 2,509 patients with breast cancer.Conclusions: ATF4 may represent a valuable prognostic biomarker and therapeutic target in patients with TNBC, and we identified a cell signaling pathway-based gene signature that may contribute to the development of combinatorial targeted therapies for breast cancer
Unveiling the environment and faint features of the isolated galaxy CIG 96 with deep optical and HI observations
Asymmetries in HI in galaxies are often caused by the interaction with close
companions, making isolated galaxies an ideal framework to study secular
evolution. The AMIGA project has demonstrated that isolated galaxies show the
lowest level of asymmetry in their HI integrated profiles, yet some present
significant asymmetries. CIG 96 (NGC 864) is a representative case reaching a
16% level. Our aim is to investigate the HI asymmetries of this spiral galaxy
and what processes have triggered the star-forming regions observed in the XUV
pseudoring. We performed deep optical observations at CAHA 1.23m, 2.2m and VST
telescopes. We reach surface brightness (SB) limits of mu_2.2m = 27.5 mag
arcsec-2 (Cous R) and mu_VST = 28.7mag arcsec-2 (r) that show the XUV
pseudoring of the galaxy in detail. Additionally, a wavelet filtering of the HI
data cube from our deep observations with E/VLA telescope allowed us to reach a
column density of N_HI = 8.9x10^18 cm -2 (5sigma) (28"x28" beam), lower than in
any isolated galaxy. We confirm that the HI extends farther than 4xr_25 in all
directions. Furthermore, we detect for the first time two gaseous structures
(10^6 Msol) in the outskirts. The g-r colour index image from 1.23m shows
extremely blue colours in certain regions of the pseudoring where
N_HI>8.5x10^20 cm-2 , whereas the rest show red colours. Galactic cirrus
contaminate the field, setting an unavoidable detection limit at 28.5mag
arcsec-2 (r). We detect no stellar link within 1degx1deg or gaseous link within
40'x40' between CIG 96 and any companion. The isolation criteria rule out
interactions with other similar-sized galaxies for at least 2.7Gyr. Using
existing stellar evolution models, the age of the pseudoring is estimated at
1Gyr or older. Undetected previously accreted companions and cold gas accretion
remain as the main hypothesis to explain the optical pseudoring and HI features
of CIG 96.Comment: 23 pages, 18 figures, 4 table
Studies of and production in and Pb collisions
The production of and mesons is studied in proton-proton and
proton-lead collisions collected with the LHCb detector. Proton-proton
collisions are studied at center-of-mass energies of and ,
and proton-lead collisions are studied at a center-of-mass energy per nucleon
of . The studies are performed in center-of-mass rapidity
regions (forward rapidity) and
(backward rapidity) defined relative to the proton beam direction. The
and production cross sections are measured differentially as a function
of transverse momentum for and , respectively. The differential cross sections are used to
calculate nuclear modification factors. The nuclear modification factors for
and mesons agree at both forward and backward rapidity, showing
no significant evidence of mass dependence. The differential cross sections of
mesons are also used to calculate cross section ratios,
which show evidence of a deviation from the world average. These studies offer
new constraints on mass-dependent nuclear effects in heavy-ion collisions, as
well as and meson fragmentation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb
public pages
Enhanced production of baryons in high-multiplicity collisions at TeV
The production rate of baryons relative to mesons
in collisions at a center-of-mass energy TeV is measured
by the LHCb experiment. The ratio of to production
cross-sections shows a significant dependence on both the transverse momentum
and the measured charged-particle multiplicity. At low multiplicity, the ratio
measured at LHCb is consistent with the value measured in
collisions, and increases by a factor of with increasing multiplicity.
At relatively low transverse momentum, the ratio of to
cross-sections is higher than what is measured in
collisions, but converges with the ratio as the momentum
increases. These results imply that the evolution of heavy quarks into
final-state hadrons is influenced by the density of the hadronic environment
produced in the collision. Comparisons with a statistical hadronization model
and implications for the mechanisms enforcing quark confinement are discussed.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-027.html (LHCb
public pages
Fraction of decays in prompt production measured in pPb collisions at TeV
The fraction of and decays in the prompt
yield, , is measured by
the LHCb detector in pPb collisions at TeV. The study
covers the forward () and backward () rapidity
regions, where is the rapidity in the nucleon-nucleon
center-of-mass system. Forward and backward rapidity samples correspond to
integrated luminosities of 13.6 0.3 nb and 20.8 0.5
nb, respectively. The result is presented as a function of the
transverse momentum in the range 1 GeV/.
The fraction at forward rapidity is compatible with the LHCb
measurement performed in collisions at TeV, whereas the
result at backward rapidity is 2.4 larger than in the forward region
for GeV/. The increase of at low at backward rapidity is compatible with the suppression of the
(2S) contribution to the prompt yield. The lack of in-medium
dissociation of states observed in this study sets an upper limit of
180 MeV on the free energy available in these pPb collisions to dissociate or
inhibit charmonium state formation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-028.html (LHCb
public pages
Observation of strangeness enhancement with charmed mesons in high-multiplicity collisions at TeV
The production of prompt and mesons is measured by the LHCb
experiment in proton-lead () collisions in both the forward
() and backward () rapidity regions at a
nucleon-nucleon center-of-mass energy of TeV.
The nuclear modification factors of both and mesons are
determined as a function of transverse momentum, , and
rapidity. In addition, the to cross-section ratio is measured
as a function of the charged particle multiplicity in the event. An enhanced
to production in high-multiplicity events is observed for the
whole measured range, in particular at low
and backward rapidity, where the significance exceeds six standard deviations.
This constitutes the first observation of strangeness enhancement in charm
quark hadronization in high-multiplicity collisions. The results
are also qualitatively consistent with the presence of quark coalescence as an
additional charm quark hadronization mechanism in high-multiplicity proton-lead
collisions.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-021.html (LHCb
public pages
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