383 research outputs found
Desertification
IPCC SPECIAL REPORT ON CLIMATE CHANGE AND LAND (SRCCL)
Chapter 3: Climate Change and Land: An IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystem
The stellar content of low redshift radio galaxies from near-infrared spectroscopy
We present medium spectral resolution near-infrared (NIR) HK-band spectra for
8 low redshift (z<0.06) radio galaxies to study the NIR stellar properties of
their host galaxies. As a homogeneous comparison sample, we used 9 inactive
elliptical galaxies that were observed with similar resolution and wavelength
range. The aim of the study is to compare the NIR spectral properties of radio
galaxies to those of inactive early-type galaxies and, furthermore, produce the
first NIR HK-band spectra for low redshift radio galaxies. For both samples
spectral indices of several diagnostic absorption features, SiI(1.589microns),
CO(1.619microns), NaI(2.207microns), CaI(2.263microns), CO(>2.29microns), were
measured. To characterize the age of the populations, the measured EWs of the
absorption features were fitted with the corresponding theoretical evolutionary
curves of the EWs calculated by the stellar synthesis model. On average, EW(CO
2.29) of radio galaxies is somewhat greater than that of inactive ellipticals.
Most likely, EW(CO 2.29) is not significantly affected by dilution, and thus
indicating that elliptical galaxies containing AGN are in a different stage in
their evolution than inactive ellipticals. This is also supported by comparing
other NIR features, such as CaI and NaI, with each other. Absorption features
are consistent with the intermediate age stellar population, suggesting that
host galaxies contain both an old and intermediate age components. It is
consistent with previous optical spectroscopy studies which have shown evidence
on the intermediate age (~2 Gyr) stellar population of radio galaxies, and also
in some of the early-type galaxies. The existence of intermediate age
population is a link between the star formation episode, possibly induced by
interaction or merging event, and the triggering of the nuclear activity.Comment: 10 pages, 7 figure
Adaptive optics near infrared integral field spectroscopy of NGC 2992
NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec
scales which might be due either to AGN or starburst activity. We therefore aim
at investigating its central region for a putative starburst in the past and
its connection to the AGN and the outflows. Observations were performed with
the adaptive optics near infrared integral field spectrograph SINFONI on the
VLT, complemented by longslit observations with ISAAC on the VLT, as well as N-
and Q-band data from the Spitzer archive. The spatial and spectral resolutions
of the SINFONI data are 50 pc and 83 km/s, respectively. The field of view of
3" x 3" corresponds to 450 pc x 450 pc. Br_gamma equivalent width and line
fluxes from PAHs were compared to stellar population models to constrain the
age of the putative recent star formation. A simple geometric model of two
mutually inclined disks and an additional cone to describe an outflow was
developed to explain the observed complex velocity field in H_2 1-0S(1). The
morphologies of the Br_gamma and the stellar continuum are different suggesting
that at least part of the Br_gamma emission comes from the AGN. This is
confirmed by PAH emission lines at 6.2 micron and 11.2 micron and the strength
of the silicon absorption feature at 9.7 micron, which point to dominant AGN
activity with a relatively minor starburst contribution. We find a starburst
age of 40 Myr - 50 Myr from Br_gamma line diagnostics and the radio continuum;
ongoing star formation can be excluded. Both the energetics and the timescales
indicate that the outflows are driven by the AGN rather than the starburst. The
complex velocity field observed in H_2 1-0S(1) in the central 450 pc can be
explained by the superposition of the galaxy rotation and an outflow.Comment: 10 pages, 8 figures, accepted for publication in A&
The Influence of Coronary Artery Disease in the Development of Aortic Stenosis and the Importance of the Albumin Redox State.
Calcific aortic valve and coronary artery diseases are related cardiovascular pathologies in which common processes lead to the calcification of the corresponding affected tissue. Among the mechanisms involved in calcification, the oxidative stress that drives the oxidation of sulfur-containing amino acids such ascysteines is of particular interest. However, there are important differences between calcific aortic valve disease and coronary artery disease, particularly in terms of the reactive oxygen substances and enzymes involved. To evaluate what effect coronary artery disease has on aortic valves, we analyzed valve tissue from patients with severe calcific aortic stenosis with and without coronary artery disease. Proteins and peptides with oxidized cysteines sites were quantified, leading to the identification of 16 proteins with different levels of expression between the two conditions studied, as well as differences in the redox state of the tissue. We also identified two specific sites of cysteine oxidation in albumin that have not been described previously. These results provide evidence that coronary artery disease affects valve calcification, modifying the molecular profile of aortic valve tissue. In addition, the redox proteome is also altered when these conditions coincide, notably affecting human serum albumin.This research was funded by the Junta de Comunidades de Castilla-La Mancha (JCCM,
co-funded by the European Social Fund, SBPLY/19/180501/000226), the Instituto de Salud Carlos
III through the project PI18/00995, PI21/00384 (co-funded by European Regional Development
Fund/European Social Fund—“Investing in your future”) Sociedad Española de Cardiología, 2020,
Grant PRB3 (IPT17/0019—ISCIII-SGEFI/ERDF), Spanish Ministry of Science, Innovation and Universities (PGC2018-097019-B-I00) and “la Caixa” Banking Foundation (project code HR17-00247). These
results are aligned with the Spanish initiative on the Human Proteome Project (SpHPP).S
EDU- SALUD. Gestión del conocimiento a través de un repositorio de objetos de Aprendizaje
Introducción: Objeto de aprendizaje (OA): recursos digitales reutilizables, con propósito educativo, constituido al menos tres componentes internos: Contenidos, actividades de aprendizaje y elementos de contextualización. Los OA son utilizados en la enseñanza y el autoaprendizaje. Edu-Salud, sitio Web de código libre, es un repositorio de OA.Objetivo: Elaborar un repositorio de OA, sustentados en web, que facilita el acceso a estos objetos mejorando el auto aprendizaje de los estudiantes de medicina, en la actividad profesional como futuro trabajador de la salud.Método. Se realizó un estudio de desarrollo en la Universidad de Ciencias Médicas de Granma, diagnosticando la utilización de los docentes y estudiantes de los OA. Se utilizaron documentos y analizaron las condiciones para la utilización de OA en la enseñanza, procesando los datos de manera computarizada, utilizando la estadística descriptiva.Resultados: El Repositorio de OA accesible desde la red de salud donde se accede a la explicación y correcto procedimiento de contenidos médicos.Conclusiones: Se elaboró un repositorio de objetos de aprendizaje, sustentados en web, facilitando el acceso a estos, mejorando el auto aprendizaje de estudiantes, en su actividad profesional como futuro trabajador de la salud.La significación social del problema de investigación, hace necesario darle un mejor uso a las nuevas tecnologías y brindar a los usuarios de la red de salud mejores medios para el aprendizaje y visualización de procedimientos médicos
Near-IR spectroscopic ages of massive star clusters in M82
Like other starburst galaxies, M82 hosts compact, massive young star clusters
that are interesting both in their own right and as benchmarks for population
synthesis models. Can spectral synthesis models at resolutions around 1000
adequately reproduce the near-IR spectral features and the energy distribution
of these clusters between 0.8 and 2.4 microns? How do the derived cluster
properties compare with previous results from optical studies?
We analyse the spectra of 5 massive clusters in M82, using data acquired with
the spectrograph SpeX on the InfraRed Telescope Facility (NASA/IRTF) and a new
population synthesis tool with a highly improved near-IR extension, based on a
recent collection of empirical and theoretical spectra of red supergiant stars.
We obtain excellent fits across the near-IR with models at quasi-solar
metallicity and a solar neighbourhood extinction law. Spectroscopy breaks a
strong degeneracy between age and extinction in the near-IR colours in the red
supergiant-dominated phase of evolution. The estimated near-IR ages cluster
between 9 and 30 Myr, i.e. the ages at which the molecular bands due to
luminous red supergiants are strongest in the current models. They do not
always agree with optical spectroscopic ages. Adding optical data sometimes
leads to the rejection of the solar neighbourhood extinction law. This is not
surprising considering small-scale structure around the clusters, but it has no
significant effect on the near-IR based spectroscopic ages. [abridged]Comment: 14 pages, 20 figures, uses aa.cl
The structural assembly switch of cell division protein FtsZ probed with fluorescent allosteric inhibitors
FtsZ is a widely conserved tubulin-like GTPase that directs bacterial cell division and a new target for antibiotic discovery. This protein assembly machine cooperatively polymerizes forming single-stranded filaments, by means of self-switching between inactive and actively associating monomer conformations. The structural switch mechanism was proposed to involve a movement of the C-terminal and N-terminal FtsZ domains, opening a cleft between them, allosterically coupled to the formation of a tight association interface between consecutive subunits along the filament. The effective antibacterial benzamide PC190723 binds into the open interdomain cleft and stabilizes FtsZ filaments, thus impairing correct formation of the FtsZ ring for cell division. We have designed fluorescent analogs of PC190723 to probe the FtsZ structural assembly switch. Among them, nitrobenzoxadiazole probes specifically bind to assembled FtsZ rather than to monomers. Probes with several spacer lengths between the fluorophore and benzamide moieties suggest a binding site extension along the interdomain cleft. These probes label FtsZ rings of live Bacillus subtilis and Staphylococcus aureus, without apparently modifying normal cell morphology and growth, but at high concentrations they induce impaired bacterial division phenotypes typical of benzamide antibacterials. During the FtsZ assembly-disassembly process, the fluorescence anisotropy of the probes changes upon binding and dissociating from FtsZ, thus reporting open and closed FtsZ interdomain clefts. Our results demonstrate the structural mechanism of the FtsZ assembly switch, and suggest that the probes bind into the open clefts in cellular FtsZ polymers preferably to unassembled FtsZ in the bacterial cytosol
Operations of and Future Plans for the Pierre Auger Observatory
Technical reports on operations and features of the Pierre Auger Observatory,
including ongoing and planned enhancements and the status of the future
northern hemisphere portion of the Observatory. Contributions to the 31st
International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
We describe the measurement of the depth of maximum, Xmax, of the
longitudinal development of air showers induced by cosmic rays. Almost four
thousand events above 10^18 eV observed by the fluorescence detector of the
Pierre Auger Observatory in coincidence with at least one surface detector
station are selected for the analysis. The average shower maximum was found to
evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/-
0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured
shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The
interpretation of these results in terms of the cosmic ray mass composition is
briefly discussed.Comment: Accepted for publication by PR
- …