A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula.

Formation of the methyl cation by photochemistry in a protoplanetary disk.

Forty years ago, it was proposed that gas-phase organic chemistry in the interstellar medium can be initiated by the methyl cation CH (refs. ), but so far it has not been observed outside the Solar System. Alternative routes involving processes on grain surfaces have been invoked.

Final Size for Epidemic Models with Asymptomatic Transmission.

The final infection size is defined as the total number of individuals that become infected throughout an epidemic. Despite its importance for predicting the fraction of the population that will end infected, it does not capture which part of the infected population will present symptoms. Knowing this information is relevant because it is related to the severity of the epidemics.

Local asymptotic stability of a system of integro-differential equations describing clonal evolution of a self-renewing cell population under mutation.

In this paper we consider a system of non-linear integro-differential equations (IDEs) describing evolution of a clonally heterogeneous population of malignant white blood cells (leukemic cells) undergoing mutation and clonal selection. We prove existence and uniqueness of non-trivial steady states and study their asymptotic stability. The results are compared to those of the system without mutation.

New molecular species at redshift = 0.89.

We present the first detections of CHSH, CH, CN, HCOOH, CHCHCN, and HCN in an extragalactic source. Namely the spiral arm of a galaxy located at z = 0.89 on the line of sight to the radio-loud quasar PKS 1830-211.

Direct estimation of electron density in the Orion Bar PDR from mm-wave carbon recombination lines.

Context: A significant fraction of the molecular gas in star-forming regions is irradiated by stellar UV photons. In these environments, the electron density ( ) plays a critical role in the gas dynamics, chemistry, and collisional excitation of certain molecules.

Aims: We determine in the prototypical strongly irradiated photodissociation region (PDR), the Orion Bar, from the detection of new millimeter-wave carbon recombination lines (mmCRLs) and existing far-IR [Cii] hyperfine line observations.

Chemical segregation of complex organic O-bearing species in Orion KL.

We investigate the chemical segregation of complex O-bearing species (including the largest and most complex ones detected to date in space) towards Orion KL, the closest high-mass star-forming region. The molecular line images obtained using the ALMA science verification data reveal a clear segregation of chemically related species depending on their different functional groups. We map the emission of CHOH, HCOOCH, CHOCH, CHOCH, CHCOOCH, HCOOCHCH, CHCHOCH, HCOOH, OHCHCHOH, CHCOOH, CHCHOH, CHOCHOH, OHCHCHO, and CHCOCH with ~1.

Molecular tracers of radiative feedback in Orion (OMC-1) Widespread CH ( = 1-0), CO (10-9), HCN (6-5), and HCO (6-5) emission.

Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud and surroundings. It is important to find tracers that help quantifying the stellar feedback processes that take place at different spatial scales. We present ~85 arcmin (~1.

Complex organic molecules in strongly UV-irradiated gas.

We investigate the presence of complex organic molecules (COMs) in strongly UV-irradiated interstellar molecular gas. We have carried out a complete millimetre (mm) line survey using the IRAM 30 m telescope towards the edge of the Orion Bar photodissociation region (PDR), close to the H dissociation front, a position irradiated by a very intense far-UV (FUV) radiation field. These observations have been complemented with 8.

Spatially resolved images of reactive ions in the Orion Bar.

We report high angular resolution (4.9″×3.0″) images of reactive ions SH, HOC, and SO toward the Orion Bar photodissociation region (PDR).

molecular photoswitching in interstellar Space.

As many organic molecules, formic acid (HCOOH) has two conformers ( and ). The energy barrier to internal conversion from to is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer () is expected to exist in detectable amounts.

Asymptotic profile in selection-mutation equations: Gauss versus Cauchy distributions.

In this paper, we study the asymptotic (large time) behaviour of a selection-mutation-competition model for a population structured with respect to a phenotypic trait when the rate of mutation is very small. We assume that the reproduction is asexual, and that the mutations can be described by a linear integral operator. We are interested in the interplay between the time variable and the rate of mutations.

Compression and ablation of the photo-irradiated molecular cloud the Orion Bar.

The Orion Bar is the archetypal edge-on molecular cloud surface illuminated by strong ultraviolet radiation from nearby massive stars. Our relative closeness to the Orion nebula (about 1,350 light years away from Earth) means that we can study the effects of stellar feedback on the parental cloud in detail. Visible-light observations of the Orion Bar show that the transition between the hot ionized gas and the warm neutral atomic gas (the ionization front) is spatially well separated from the transition between atomic and molecular gas (the dissociation front), by about 15 arcseconds or 6,200 astronomical units (one astronomical unit is the Earth-Sun distance).

VELOCITY-RESOLVED [C ii] EMISSION AND [C ii]/FIR MAPPING ALONG ORION WITH .

We present the first ~7.5'×11.5' velocity-resolved (~0.

Revised spectroscopic parameters of SH(+) from ALMA and IRAM 30m observations.

Hydrides represent the first steps of interstellar chemistry. Sulfanylium (SH(+)), in particular, is a key tracer of energetic processes. We used ALMA and the IRAM 30 m telescope to search for the lowest frequency rotational lines of SH(+) toward the Orion Bar, the prototypical photo-dissociation region illuminated by a strong UV radiation field.

Coming of age: a review of embodiment and the neuroscience of semantics.

Over the last decade, there has been an increasing body of work that explores whether sensory and motor information is a necessary part of semantic representation and processing. This is the embodiment hypothesis. This paper presents a theoretical review of this work that is intended to be useful for researchers in the neurosciences and neuropsychology.

Stability of equilibria of a predator-prey model of phenotype evolution.

We consider a selection mutation predator-prey model for the distribution of individuals with respect to an evolutionary trait. Local stability of the equilibria of this model is studied using the linearized stability principle and taking advantage of the (assumed) asymptotic stability of the equilibria of the resident population adopting an evolutionarily stable strategy.

Differential control of isocitrate lyase gene transcription by non-fermentable carbon sources in the milk yeast Kluyveromyces lactis.

The KlICL1 gene, encoding isocitrate lyase in Kluyveromyces lactis, is essential for ethanol utilization. Deletion analyses identified two functional promoter elements, CSRE-A and CSRE-B. Transcription is activated on ethanol, but not on glucose, glycerol or lactate.

Asymptotic stability of equilibria of selection-mutation equations.

We study local stability of equilibria of selection-mutation equations when mutations are either very small in size or occur with very low probability. The main mathematical tools are the linearized stability principle and the fact that, when the environment (the nonlinearity) is finite dimensional, the linearized operator at the steady state turns out to be a degenerate perturbation of a known operator with spectral bound equal to 0. An example is considered where the results on stability are applied.

Adaptive dynamics via Hamilton-Jacobi approach and entropy methods for a juvenile-adult model.

We consider a nonlinear system describing a juvenile-adult population undergoing small mutations. We analyze two aspects: from a mathematical point of view, we use an entropy method to prove that the population neither goes extinct nor blows-up; from an adaptive evolution point of view, we consider small mutations on a long time scale and study how a monomorphic or a dimorphic initial population evolves towards an Evolutionarily Stable State. Our method relies on an asymptotic analysis based on a constrained Hamilton-Jacobi equation.

External sense organs in freshwater oligochaetes (Annelida, Clitellata) revealed by scanning electron microscopy.

Freshwater oligochaetes have at least two kinds of external sense organs: multiciliate organs of short cilia (also present in earthworms) and sense organs with one to three long cilia (unknown in earthworms and possibly acting as rheoreceptors). Ciliate sense organs of freshwater oligochaetes are distributed over their entire body surface, including the clitellum. They are scattered on the prostomium and pigidium and are arranged into a transversal chaetal row and dispersed or forming a few other discrete transversal rows on chaetal segments.

Small mutation rate and evolutionarily stable strategies in infinite dimensional adaptive dynamics.

An integrodifferential equations model for the distribution of individuals with respect to the age at maturity is considered. Mutation is modeled by an integral operator. Results concerning the behaviour of the steady states and their relation to evolutionarily stable strategies when the mutation rate is small are given.

Protective effects of lazaroid U74389G on intestinal graft after heterotopic small bowel transplantation in rats.

Background: Experimental studies have shown that 21-aminosteroids (21-A) are powerful inhibitors of superoxide-mediated iron-dependent lipid peroxidation. This study was aimed at determining how far the blocking effect of one of these substances (lazaroid U74389G) on lipid peroxidation protects intestinal grafts morphologically and biologically in a heterotopic transplant model (SBT) in rats.

Animals And Methods: Heterotopic LEW were performed using Ringer lactate (4 degrees C) as preservation solution.

Effect of oral supplementation of ornithine-alpha-ketoglutarate on the intestinal barrier after orthotopic small bowel transplantation.

The aim of this study was to analyze the possible protective effects of a glutamine and arginine precursor (ornithine-alpha-ketoglutarate [OKG]) on the mucosa of a transplanted intestine when administered with either a defined formula oral diet (DFD) or a standard chow. Isogenic male Lewis rats (250 g) were submitted to a laparotomy (groups 1 and 2) or to an orthotopic small bowel transplantation (SBT; groups 3-6). Groups 1, 3, and 5 received a DFD 14 days after surgery.