185 research outputs found
FLI-1 Flightless-1 and LET-60 Ras control germ line morphogenesis in C. elegans
Background: In the C. elegans germ line, syncytial germ line nuclei are arranged at the cortex of the germ line as they exit mitosis and enter meiosis, forming a nucleus-free core of germ line cytoplasm called the rachis. Molecular mechanisms of rachis formation and germ line organization are not well understood.
Results: Mutations in the fli-1 gene disrupt rachis organization without affecting meiotic differentiation, a phenotype in C. elegans referred to here as the
g
erm
l
ine
m
orphogenesis (Glm) phenotype. In fli-1 mutants, chains of meiotic germ nuclei spanned the rachis and were partially enveloped by invaginations of germ line plasma membrane, similar to nuclei at the cortex. Extensions of the somatic sheath cells that surround the germ line protruded deep inside the rachis and were associated with displaced nuclei in fli-1 mutants. fli-1 encodes a molecule with leucine-rich repeats and gelsolin repeats similar to Drosophila flightless 1 and human Fliih, which have been shown to act as cytoplasmic actin regulators as well as nuclear transcriptional regulators. Mutations in let-60 Ras, previously implicated in germ line development, were found to cause the Glm phenotype. Constitutively-active LET-60 partially rescued the fli-1 Glm phenotype, suggesting that LET-60 Ras and FLI-1 might act together to control germ line morphogenesis.
Conclusion: FLI-1 controls germ line morphogenesis and rachis organization, a process about which little is known at the molecular level. The LET-60 Ras GTPase might act with FLI-1 to control germ line morphogenesis
Cgwind: A high-order accurate simulation tool for wind turbines and wind farms
ABSTRACT: CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans
Measurements in support of wind farm simulations and power forecasts: The Crop/Wind-energy Experiments (CWEX)
The Midwest US currently is experiencing a large build-out of wind turbines in areas where the nocturnal low-level jet (NLLJ) is a prominent and frequently occurring feature. We describe shear characteristics of the NLLJ and their influence on wind power production. Reports of individual turbine power production and concurrent measurements of near-surface thermal stratification are used to turbine wake interactions and turbine interaction with the overlying atmosphere. Progress in forecasting conditions such as wind ramps and shear are discussed. Finally, the pressure perturbation introduced by a line of turbines produces surface flow convergence that may create a vertical velocity and hence a mesoscale influence on cloud formation by a wind farm
Correction: Managing Climate Change Refugia for Climate Adaptation.
[This corrects the article DOI: 10.1371/journal.pone.0159909.]
CASES-99: a comprehensive investigation of the stable nocturnal boundary layer
The Cooperative Atmosphere-Surface Exchange Study—1999 (CASES-99) refers to a field experiment carried out in southeast Kansas during October 1999 and the subsequent program of investigation. Comprehensive data, primarily taken during the nighttime but typically including the evening and morning transition, supports data analyses, theoretical studies, and state-of-the-art numerical modeling in a concerted effort by participants to investigate four areas of scientific interest. The choice of these scientific topics is motivated by both the need to delineate physical processes that characterize the stable boundary layer, which are as yet not clearly understood, and the specific scientific goals of the investigators. Each of the scientific goals should be largely achievable with the measurements taken, as is shown with preliminary analysis within the scope of three of the four scientific goals. Underlying this effort is the fundamental motivation to eliminate deficiencies in surface layer and turbulent diffusion parameterizations in atmospheric models, particularly where the Richardson number exceeds 0.25. This extensive nocturnal boundary layer (NBL) dataset is available to the scientific community at large, and the CASES-99 participants encourage all interested parties to utilize it.Carmen Nappo acknowledges the support of the U.S. Army Research Laboratory under Grant MIPROB-NOAA007. JS and SB acknowledge the support of Army Research Office Grant DAAD 1999- 1-0320, National Science Foundation Grant ATM-9906637.
JC and ET acknowledge the Spanish Commission for Science and Technology through Projects CLI97-0343 and CLI99-1326- E
Modulational instability of solitary waves in non-degenerate three-wave mixing: The role of phase symmetries
We show how the analytical approach of Zakharov and Rubenchik [Sov. Phys.
JETP {\bf 38}, 494 (1974)] to modulational instability (MI) of solitary waves
in the nonlinear Schr\"oedinger equation (NLS) can be generalised for models
with two phase symmetries. MI of three-wave parametric spatial solitons due to
group velocity dispersion (GVD) is investigated as a typical example of such
models. We reveal a new branch of neck instability, which dominates the usual
snake type MI found for normal GVD. The resultant nonlinear evolution is
thereby qualitatively different from cases with only a single phase symmetry.Comment: 4 pages with figure
SAGUARO: Time-domain Infrastructure for the Fourth Gravitational-wave Observing Run and Beyond
We present upgraded infrastructure for Searches after Gravitational Waves
Using ARizona Observatories (SAGUARO) during LIGO, Virgo, and KAGRA's fourth
gravitational-wave (GW) observing run (O4). These upgrades implement many of
the lessons we learned after a comprehensive analysis of potential
electromagnetic counterparts to the GWs discovered during the previous
observing run. We have developed a new web-based target and observation manager
(TOM) that allows us to coordinate sky surveys, vet potential counterparts, and
trigger follow-up observations from one centralized portal. The TOM includes
software that aggregates all publicly available information on the light curves
and possible host galaxies of targets, allowing us to rule out potential
contaminants like active galactic nuclei, variable stars, solar-system objects,
and preexisting supernovae, as well as to assess the viability of any plausible
counterparts. We have also upgraded our image-subtraction pipeline by
assembling deeper reference images and training a new neural network-based
real-bogus classifier. These infrastructure upgrades will aid coordination by
enabling the prompt reporting of observations, discoveries, and analysis to the
GW follow-up community, and put SAGUARO in an advantageous position to discover
kilonovae in the remainder of O4 and beyond. Many elements of our open-source
software stack have broad utility beyond multimessenger astronomy, and will be
particularly relevant in the "big data" era of transient discoveries by the
Vera C. Rubin Observatory.Comment: submitted to AAS Journal
Educational attainment does not influence brain aging.
Education has been related to various advantageous lifetime outcomes. Here, using longitudinal structural MRI data (4,422 observations), we tested the influential hypothesis that higher education translates into slower rates of brain aging. Cross-sectionally, education was modestly associated with regional cortical volume. However, despite marked mean atrophy in the cortex and hippocampus, education did not influence rates of change. The results were replicated across two independent samples. Our findings challenge the view that higher education slows brain aging
Report On The Workshop ‘Global Modelling Of Biodiversity And Ecosystem Services’
A three-day workshop on ‘Global Modelling of Biodiversity and Ecosystem Services’, was held in the Hague, Netherlands, from 24th to 26th June 2019. The workshop, attended by 35 modelling and scenario-building experts, was organised on behalf of the former IPBES 1 expert group on scenarios and models of the first IPBES work programme by its interim technical support unit, and hosted by the PBL Netherlands Environmental Assessment Agency.
The workshop drew on the ‘nature futures’ participatory scenario-building exercise initiated by the IPBES expert group on scenarios and models, and other biodiversity modelling initiatives such as the ISIMIP project 2 working on adding biodiversity to the Shared Socioeconomic Pathways (SSPs) scenarios framework, the'bending the curve'initiative 3 led by IIASA 4 and WWF 5, and GEOBON 6 working on modelling Essential Biodiversity Variables. The workshop was a step towards coordinating across biodiversity modelling initiatives, to build on each other’s work, and to seek synergies for the production of innovative scenarios on biodiversity and ecosystem services to inform the post-2020 agenda of the Convention on Biological Diversity, as well as the Sustainable Development Goal
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