21 research outputs found
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument
The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
The Habitable Exoplanet Observatory, or HabEx, has been designed to be the
Great Observatory of the 2030s. For the first time in human history,
technologies have matured sufficiently to enable an affordable space-based
telescope mission capable of discovering and characterizing Earthlike planets
orbiting nearby bright sunlike stars in order to search for signs of
habitability and biosignatures. Such a mission can also be equipped with
instrumentation that will enable broad and exciting general astrophysics and
planetary science not possible from current or planned facilities. HabEx is a
space telescope with unique imaging and multi-object spectroscopic capabilities
at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities
allow for a broad suite of compelling science that cuts across the entire NASA
astrophysics portfolio. HabEx has three primary science goals: (1) Seek out
nearby worlds and explore their habitability; (2) Map out nearby planetary
systems and understand the diversity of the worlds they contain; (3) Enable new
explorations of astrophysical systems from our own solar system to external
galaxies by extending our reach in the UV through near-IR. This Great
Observatory science will be selected through a competed GO program, and will
account for about 50% of the HabEx primary mission. The preferred HabEx
architecture is a 4m, monolithic, off-axis telescope that is
diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two
starlight suppression systems: a coronagraph and a starshade, each with their
own dedicated instrument.Comment: Full report: 498 pages. Executive Summary: 14 pages. More information
about HabEx can be found here: https://www.jpl.nasa.gov/habex
Cost Validation Using PRICE H
PRICE H was introduced into the JPL cost estimation tool set circa 2003. It became more available at JPL when IPAO funded the NASA-wide site license for all NASA centers. PRICE H was mainly used as one of the cost tools to validate proposal grassroots cost estimates. Program offices at JPL view PRICE H as an additional crosscheck to Team X (JPL Concurrent Engineering Design Center) estimates. PRICE H became widely accepted ca, 2007 at JPL when the program offices moved away from grassroots cost estimation for Step 1 proposals. PRICE H is now one of the key cost tools used for cost validation, cost trades, and independent cost estimates
Seismic site effects in the Red Zone of Amatrice hill detected via the mutual sustainment of experimental and computational approaches
This paper presents the results of numerical analyses of ground motion in the Red Zone sector of Amatrice hill, violently struck by the 2016–2017 Central Italy seismic sequence. The methodologies used in processing the data to define the numerical model are firstly described. The results obtained from the computational analyses are then presented and discussed by comparing them with experimental data set of weak motion recordings. Computational analyses were performed via both a 2D-numerical FEM model and a pseudo-three-dimensional hybrid model (SiSeRHMap) which develops multispectral maps taking into account topographic effects. Starting from available geological data and geophysical measurements, an original and specific subsoil GIS model was developed and utilised to perform the computational analyses. The preliminary map for fundamental periods computed from the subsoil model is in good agreement with the experimental data. A restricted set of weak ground motions acquired from an accelerometric station located in a reference site was used as input for the numerical analyses, while the signals of the corresponding events recorded at the top of the hill were used as targets in the reliability evaluation analysis of the outputs. In the area of Amatrice hill, which is characterized by a complex geological and topographical context, the reliability analysis shows a good performance of the hybrid model compared to the 2D-FEM model in the prediction of seismic response. Agreement generally was also good with regards to the experimental and computational results, both in relation to the amplitude and to the shape of the spectral amplification that change depending on the hill sector. Considering the predictive reliability of the models, a high amplification, due to topographic effects, was observed for the Red Zone by performing a back-simulation of the 24th August 2016 main shock. The analysis results highlight also that the maximum amplification factors, based on the definition of the Housner intensity, occur in the interval of periods 0–0.5 s covering the fundamental period range of the buildings in this area