187 research outputs found
Density biases and temperature relations for DESIRED HII regions
We present a first study based on the analysis of the DEep Spectra of Ionized
REgions Database (DESIRED). This is a compilation of 190 high signal-to-noise
ratio optical spectra of HII regions and other photoionized nebulae, mostly
observed with 8-10m telescopes and containing 29380 emission lines. We
find that the electron density ---- of the objects is underestimated
when [SII] and/or [OII] are
the only density indicators available. This is produced by the non-linear
density dependence of the indicators in the presence of density
inhomogeneities. The average underestimate is cm in
extragalactic HII regions, introducing systematic overestimates of ([OII]) and ([SII]) compared to ([NII]). The
high-sensitivity of [OII]
and [SII] to density makes them
more suitable for the diagnosis of the presence of high-density clumps. If
([NII]) is adopted, the density underestimate has a small impact in
the ionic abundances derived from optical spectra, being limited to up to
0.1 dex when auroral [SII] and/or [OII] lines are used. However, these
density effects are critical for the analysis of infrared fine structure lines,
such as those observed by the JWST in local star forming regions, implying
strong underestimates of the ionic abundances. We present temperature relations
between ([OIII]), ([ArIII]), ([SIII]) and
([NII]) for the extragalactic HII regions. We confirm a non-linear
dependence between ([OIII])-([NII]) due to a more rapid
increase of ([OIII]) at lower metallicities.Comment: Accepted for publication in MNRA
Generalized Toda Theory from Six Dimensions and the Conifold
Recently, a physical derivation of the Alday-Gaiotto-Tachikawa correspondence
has been put forward. A crucial role is played by the complex Chern-Simons
theory arising in the 3d-3d correspondence, whose boundary modes lead to Toda
theory on a Riemann surface. We explore several features of this derivation and
subsequently argue that it can be extended to a generalization of the AGT
correspondence. The latter involves codimension two defects in six dimensions
that wrap the Riemann surface. We use a purely geometrical description of these
defects and find that the generalized AGT setup can be modeled in a pole region
using generalized conifolds. Furthermore, we argue that the ordinary conifold
clarifies several features of the derivation of the original AGT
correspondence.Comment: 27+2 pages, 3 figure
Single-molecule experiments in biological physics: methods and applications
I review single-molecule experiments (SME) in biological physics. Recent
technological developments have provided the tools to design and build
scientific instruments of high enough sensitivity and precision to manipulate
and visualize individual molecules and measure microscopic forces. Using SME it
is possible to: manipulate molecules one at a time and measure distributions
describing molecular properties; characterize the kinetics of biomolecular
reactions and; detect molecular intermediates. SME provide the additional
information about thermodynamics and kinetics of biomolecular processes. This
complements information obtained in traditional bulk assays. In SME it is also
possible to measure small energies and detect large Brownian deviations in
biomolecular reactions, thereby offering new methods and systems to scrutinize
the basic foundations of statistical mechanics. This review is written at a
very introductory level emphasizing the importance of SME to scientists
interested in knowing the common playground of ideas and the interdisciplinary
topics accessible by these techniques. The review discusses SME from an
experimental perspective, first exposing the most common experimental
methodologies and later presenting various molecular systems where such
techniques have been applied. I briefly discuss experimental techniques such as
atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers
(MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I
then present several applications of SME to the study of nucleic acids (DNA,
RNA and DNA condensation), proteins (protein-protein interactions, protein
folding and molecular motors). Finally, I discuss applications of SME to the
study of the nonequilibrium thermodynamics of small systems and the
experimental verification of fluctuation theorems. I conclude with a discussion
of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond.
Matt
N = 1 dualities in 2+1 dimensions
We consider minimally supersymmetric QCD in 2+1 dimensions, with Chern-Simons
and superpotential interactions. We propose an infrared duality involving gauge-singlet fields on one of the two sides. It shares
qualitative features both with 3d bosonization and with 4d Seiberg duality. We
provide a few consistency checks of the proposal, mapping the structure of
vacua and performing perturbative computations in the -expansion
Comparative performance of the mussels Perna perna and Perna viridis, cultivated at four different depths
Maternal Infection with Trypanosoma cruzi and Congenital Chagas Disease Induce a Trend to a Type 1 Polarization of Infant Immune Responses to Vaccines
Vaccines are of crucial importance to prevent morbidity and mortality due to infectious diseases in childhood. A modulation of the fetal/neonatal immune system (considered immature) toward Th1 or Th2 dominance could modify responses to vaccines administered in early life. T. cruzi is the agent of Chagas' disease, in Latin America currently infecting about 2 million women at fertile ages who are susceptible to transmitting the parasite to their fetus. In previous studies we showed that T. cruzi-infected mothers can induce a pro-inflammatory environment in their uninfected neonates (M+B−), whereas congenitally infected newborns (M+B+) are able to develop a pro-Th1 parasite-specific T cell response. In the present study, we analysed the cellular and/or antibody responses to Bacillus Calmette Guerin (BCG), hepatitis B birus (HBV), diphtheria and tetanus vaccines in 6- to 7-month-old infants living in Bolivia. M+B− infants produced more IFN-γ in response to BCG, whereas M+B+ infants developed a stronger IFN-γ response to hepatitis B, diphtheria and tetanus vaccines and enhanced antibody production to HBs antigen. These results show that both maternal infection with T. cruzi and congenital Chagas disease do not interfere with responses to BCG, hepatitis B, diphtheria and tetanus vaccines in the neonatal period and that T. cruzi infection in early life tends to favour type 1 immune responses to vaccinal antigens
Pode a termografia auxiliar no diagnóstico de lesões musculares em atletas de futebol?
Integrating views on support for mid-level health worker performance: a concept mapping study with regional health system actors in rural Guatemala
Type 2 Diabetes Variants Disrupt Function of SLC16A11 through Two Distinct Mechanisms
Type 2 diabetes (T2D) affects Latinos at twice the rate seen in populations of European descent. We recently identified a risk haplotype spanning SLC16A11 that explains ∼20% of the increased T2D prevalence in Mexico. Here, through genetic fine-mapping, we define a set of tightly linked variants likely to contain the causal allele(s). We show that variants on the T2D-associated haplotype have two distinct effects: (1) decreasing SLC16A11 expression in liver and (2) disrupting a key interaction with basigin, thereby reducing cell-surface localization. Both independent mechanisms reduce SLC16A11 function and suggest SLC16A11 is the causal gene at this locus. To gain insight into how SLC16A11 disruption impacts T2D risk, we demonstrate that SLC16A11 is a proton-coupled monocarboxylate transporter and that genetic perturbation of SLC16A11 induces changes in fatty acid and lipid metabolism that are associated with increased T2D risk. Our findings suggest that increasing SLC16A11 function could be therapeutically beneficial for T2D. Video Abstract [Figure presented] Keywords: type 2 diabetes (T2D); genetics; disease mechanism; SLC16A11; MCT11; solute carrier (SLC); monocarboxylates; fatty acid metabolism; lipid metabolism; precision medicin
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