1,181 research outputs found
A near-IR line of Mn I as a diagnostic tool of the average magnetic energy in the solar photosphere
We report on spectropolarimetric observations of a near-IR line of Mn I
located at 15262.702 A whose intensity and polarization profiles are very
sensitive to the presence of hyperfine structure. A theoretical investigation
of the magnetic sensitivity of this line to the magnetic field uncovers several
interesting properties. The most important one is that the presence of strong
Paschen-Back perturbations due to the hyperfine structure produces an intensity
line profile whose shape changes according to the absolute value of the
magnetic field strength. A line ratio technique is developed from the intrinsic
variations of the line profile. This line ratio technique is applied to
spectropolarimetric observations of the quiet solar photosphere in order to
explore the probability distribution function of the magnetic field strength.
Particular attention is given to the quietest area of the observed field of
view, which was encircled by an enhanced network region. A detailed theoretical
investigation shows that the inferred distribution yields information on the
average magnetic field strength and the spatial scale at which the magnetic
field is organized. A first estimation gives ~250 G for the mean field strength
and a tentative value of ~0.45" for the spatial scale at which the observed
magnetic field is horizontally organized.Comment: 42 pages, 17 figures, accepted for publication in the Astrophysical
Journal. Figures 1 and 9 are in JPG forma
Inflationary Quasiparticle Creation and Thermalization Dynamics in Coupled Bose-Einstein Condensates
A Bose gas in a double-well potential, exhibiting a true Bose-Einstein
condensate (BEC) amplitude and initially performing Josephson oscillations, is
a prototype of an isolated, non-equilibrium many-body system. We investigate
the quasiparticle (QP) creation and thermalization dynamics of this system by
solving the time-dependent Keldysh-Bogoliubov equations. We find avalanche-like
QP creation due to a parametric resonance between BEC and QP oscillations,
followed by slow, exponential relaxation to a thermal state at an elevated
temperature, controlled by the initial excitation energy of the oscillating BEC
above its ground state. The crossover between the two regimes occurs because of
an effective decoupling of the QP and BEC oscillations. This dynamics is
analogous to elementary particle creation in models of the early universe. The
thermalization in our set-up occurs because the BEC acts as a grand canonical
reservoir for the quasiparticle system.Comment: 5 pages, 4 Figures, final version accepted for publication in Phys.
Rev. Let
Aberrant innate immune sensing leads to the rapid progression of idiopathic pulmonary fibrosis
Novel approaches are needed to define subgroups of patients with Idiopathic pulmonary fibrosis (IPF) at risk for acute exacerbations and/or accelerated progression of this generally fatal disease. Progression of disease is an integral component of IPF with a median survival of 3 to 5 years. Conversely, a high degree of variability in disease progression has been reported among series. The characteristics of patients at risk of earlier death predominantly rely on baseline HRCT appearance, but this concept that has been challenged. Disparate physiological approaches have also been taken to identify patients at risk of mortality, with varying results. We hypothesized that the rapid decline in lung function in IPF may be a consequence of an abnormal host response to pathogen-associated molecular patterns (PAMPs), leading to aberrant activation in fibroblasts and fibrosis. Analysis of upper and lower lobe surgical lung biopsies (SLBs) indicated that TLR9, a hypomethylated CpG DNA receptor, is prominently expressed at the transcript and protein level, most notably in biopsies from rapidly progressive IPF patients. Surprisingly, fibroblasts appeared to be a major cellular source of TLR9 expression in IPF biopsies from this group of progressors. Further, CpG DNA promoted profibrotic cytokine and chemokine synthesis in isolated human IPF fibroblasts, most markedly again in cells from patients with the rapidly progressive IPF phenotype, in a TLR9-dependent manner. Finally, CpG DNA exacerbated fibrosis in an in vivo model initiated by the adoptive transfer of primary fibroblasts derived from patients who exhibited rapidly progressing fibrosis. Together, these data suggested that TLR9 activation via hypomethylated DNA might be an important mechanism in promoting fibrosis particularly in patients prone to rapidly progressing IPF
Proper motions of the HH1 jet
We describe a new method for determining proper motions of extended objects,
and a pipeline developed for the application of this method. We then apply this
method to an analysis of four epochs of [S~II] HST images of the HH~1 jet
(covering a period of ~yr).
We determine the proper motions of the knots along the jet, and make a
reconstruction of the past ejection velocity time-variability (assuming
ballistic knot motions). This reconstruction shows an "acceleration" of the
ejection velocities of the jet knots, with higher velocities at more recent
times. This acceleration will result in an eventual merging of the knots in
~yr and at a distance of from the outflow source, close to
the present-day position of HH~1.Comment: 12 pages, 8 figure
Hierarchical Catalysts Prepared by Interzeolite Transformation
Interzeolite transformation has been used to produce a novel family of hierarchical catalysts featuring excellent textural properties, strong acidity, and superior catalytic performance for the Friedel–Crafts alkylation of indole with benzhydrol, the Claisen–Schmidt condensation of benzaldehyde and hydroxyacetophenone, and the cracking of polystyrene. Intermediate solids of the FAU interzeolite transformation into BEA display both increased accessibility─due to the development of mesoporosity─and strong acidity─caused by the presence of ultrasmall crystals or zeolitic fragments in their structure. The use of surfactants allows for the development of the hierarchical catalysts with very narrow pore size distribution. The properties of interzeolite transformation intermediates (ITIs) can be fine-tuned simply by stopping the interconversion at different times.The authors thank the European Commission for funding through the H2020-MSCA-RISE-2019 program (Ref. ZEOBIOCHEM-872102) and the Spanish MINECO and AEI/FEDER, UE, through Project Ref. RTI2018-099504-B-C21. N.L. also acknowledges the University of Alicante support (UATALENTO17-05). M.J.M. thanks the Generalitat Valenciana for a PhD fellowship (GRISOLIAP/2020/165). Carlos A. Trujillo and Nelcari T. Ramírez M. express their gratitude to the Universidad Nacional de Colombia for providing physical and technical resources for this research also to Minciencias and Ecopetrol in the frame of Contract 0402-2013
4-1BBL as a Mediator of Cross-Talk between Innate, Adaptive, and Regulatory Immunity against Cancer
The ability of tumor cells to evade the immune system is one of the main challenges we confront in the fight against cancer. Multiple strategies have been developed to counteract this situation, including the use of immunostimulant molecules that play a key role in the anti-tumor immune response. Such a response needs to be tumor-specific to cause as little damage as possible to healthy cells and also to track and eliminate disseminated tumor cells. Therefore, the combination of immunostimulant molecules and tumor-associated antigens has been implemented as an antitumor therapy strategy to eliminate the main obstacles confronted in conventional therapies. The immunostimulant 4-1BBL belongs to the tumor necrosis factor (TNF) family and it has been widely reported as the most effective member for activating lymphocytes. Hence, we will review the molecular, pre-clinical, and clinical applications in conjunction with tumor-associated antigens in antitumor immunotherapy, as well as the main molecular pathways involved in this association
Entropy based parametrization of soils: Models and Tools
Particle-size distribution (PSD) is a fundamental soil physical property. The PSD is commonly reported in terms of the mass percentages of sand, silt and clay present
Satellites around massive galaxies since z~2
Accretion of minor satellites has been postulated as the most likely
mechanism to explain the significant size evolution of the massive galaxies
over cosmic time. Using a sample of 629 massive (Mstar~10^11 Msun) galaxies
from the near-infrared Palomar/DEEP-2 survey, we explore which fraction of
these objects has satellites with 0.01 Msat < Mcentral < 1 (1:100) up to z=1
and which fraction has satellites with 0.1 Msat < Mcentral < 1 (1:10) up to z=2
within a projected radial distance of 100 kpc. We find that the fraction of
massive galaxies with satellites, after the background correction, remains
basically constant and close to ~30% for satellites with a mass ratio down to
1:100 up to z=1, and ~15% for satellites with a 1:10 mass ratio up to z=2. The
family of spheroid-like massive galaxies presents a 2-3 times larger fraction
of objects with satellites than the group of disk-like massive galaxies. A
crude estimation of the number of 1:3 mergers a massive spheroid-like galaxy
experiences since z~2 is around 2. For a disk-like galaxy this number decreases
to ~1.Comment: 8 pages, 7 figures, 2 tables. Submitted to MNRAS on Sept. 23,
resubmitted after addressing referee comment
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