123 research outputs found
VLBI measurement of the vector baseline between geodetic antennas at Kokee Park Geophysical Observatory, Hawaii
We measured the components of the 31-m-long vector between the two
Very-Long-Baseline Interferometry (VLBI) antennas at the Kokee Park Geophysical
Observatory (KPGO), Hawaii, with approximately 1 mm precision using phase-delay
observables from dedicated VLBI observations in 2016 and 2018. The two KPGO
antennas are the 20 m legacy VLBI antenna and the 12 m VLBI Global Observing
System (VGOS) antenna. Independent estimates of the vector between the two
antennas were obtained by the National Geodetic Survey (NGS) using standard
optical surveys in 2015 and 2018. The uncertainties of the latter survey were
0.3 and 0.7 mm in the horizontal and vertical components of the baseline,
respectively. We applied corrections to the measured positions for the varying
thermal deformation of the antennas on the different days of the VLBI and
survey measurements, which can amount to 1 mm, bringing all results to a common
reference temperature. The difference between the VLBI and survey results are
0.2 +/- 0.4 mm, -1.3 +/- 0.4 mm, and 0.8 +/- 0.8 mm in the East, North, and Up
topocentric components, respectively. We also estimate that the Up component of
the baseline may suffer from systematic errors due to gravitational deformation
and uncalibrated instrumental delay variations at the 20 m antenna that may
reach +/-10 mm and -2 mm, respectively, resulting in an accuracy uncertainty on
the order of 10 mm for the relative heights of the antennas. Furthermore,
possible tilting of the 12 m antenna increases the uncertainties in the
differences in the horizontal components to 1.0 mm. These results bring into
focus the importance of (1) correcting to a common reference temperature the
measurements of the reference points of all geodetic instruments within a site,
(2) obtaining measurements of the gravitational deformation of all antennas,
and (3) monitoring local motions of the geodetic instruments.Comment: 34 pages, 4 figures, to be published in Journal of Geodes
Nuclear rupture at sites of high curvature compromises retention of DNA repair factors.
The nucleus is physically linked to the cytoskeleton, adhesions, and extracellular matrix-all of which sustain forces, but their relationships to DNA damage are obscure. We show that nuclear rupture with cytoplasmic mislocalization of multiple DNA repair factors correlates with high nuclear curvature imposed by an external probe or by cell attachment to either aligned collagen fibers or stiff matrix. Mislocalization is greatly enhanced by lamin A depletion, requires hours for nuclear reentry, and correlates with an increase in pan-nucleoplasmic foci of the DNA damage marker γH2AX. Excess DNA damage is rescued in ruptured nuclei by cooverexpression of multiple DNA repair factors as well as by soft matrix or inhibition of actomyosin tension. Increased contractility has the opposite effect, and stiff tumors with low lamin A indeed exhibit increased nuclear curvature, more frequent nuclear rupture, and excess DNA damage. Additional stresses likely play a role, but the data suggest high curvature promotes nuclear rupture, which compromises retention of DNA repair factors and favors sustained damage
AMPK is a mechano-metabolic sensor linking cell adhesion and mitochondrial dynamics to Myosin-dependent cell migration
Cell migration is crucial for cancer dissemination. We find that AMP-activated protein kinase (AMPK) controls cell migration by acting as an adhesion sensing molecular hub. In 3-dimensional matrices, fast-migrating amoeboid cancer cells exert low adhesion/low traction linked to low ATP/AMP, leading to AMPK activation. In turn, AMPK plays a dual role controlling mitochondrial dynamics and cytoskeletal remodelling. High AMPK activity in low adhering migratory cells, induces mitochondrial fission, resulting in lower oxidative phosphorylation and lower mitochondrial ATP. Concurrently, AMPK inactivates Myosin Phosphatase, increasing Myosin II-dependent amoeboid migration. Reducing adhesion or mitochondrial fusion or activating AMPK induces efficient rounded-amoeboid migration. AMPK inhibition suppresses metastatic potential of amoeboid cancer cells in vivo, while a mitochondrial/AMPK-driven switch is observed in regions of human tumours where amoeboid cells are disseminating. We unveil how mitochondrial dynamics control cell migration and suggest that AMPK is a mechano-metabolic sensor linking energetics and the cytoskeleton. Cell metabolism must adapt to the energy needs of migrating cells. This study finds that fast amoeboid migrating cells harbor high AMPK activity, which controls both mitochondrial dynamics and cytoskeletal remodeling, enabling reduced energy needs
Spatial and Temporal Melt Variability at Helheim Glacier, East Greenland, and Its Effect on Ice Dynamics
Understanding the behavior of large outlet glaciers draining the Greenland Ice Sheet is critical for assessing the impact of climate change on sea level rise. The flow of marine-terminating outlet glaciers is partly governed by calving-related processes taking place at the terminus but is also influenced by the drainage of surface runoff to the bed through moulins, cracks, and other pathways. To investigate the extent of the latter effect, we develop a distributed surface-energy-balance model for Helheim Glacier, East Greenland, to calculate surface melt and thereby estimate runoff. The model is driven by data from an automatic weather station operated on the glacier during the summers of 2007 and 2008, and calibrated with independent measurements of ablation. Modeled melt varies over the deployment period by as much as 68% relative to the mean, with melt rates approximately 77% higher on the lower reaches of the glacier trunk than on the upper glacier. We compare melt variations during the summer season to estimates of surface velocity derived from global positioning system surveys. Near the front of the glacier, there is a significant correlation (on \u3e95% levels) between variations in runoff (estimated from surface melt) and variations in velocity, with a 1 day delay in velocity relative to melt. Although the velocity changes are small compared to accelerations previously observed following some calving events, our findings suggest that the flow speed of Helheim Glacier is sensitive to changes in runoff. The response is most significant in the heavily crevassed, fast-moving region near the calving front. The delay in the peak of the cross-correlation function implies a transit time of 12-36 h for surface runoff to reach the bed
Revista de Vertebrados de la Estación Biológica de Doñana
Ritmo diario de actividad social en (Gambusia affinis)Sobre la herpetofauna de la Sierra de Estrella (Portugal) con especial referencia a Coronella austriaca austriaca y Vipera latastiNuevos datos sobre la distribución geográfica de los anfibios y reptiles ibéricosBiogeografía en la evolución de un grupo de formas de Coluber en el Paleártico OccidentalDatos sobre la alimentación de ofidiosEstructura de las galerías de nidificación del Abejaruco (Merops apiaster) en DoñanaComportamiento de la Perdiz Moruna ( Alectoris barbara) en cautividadEl paso otoñal de Sylvia borin y Sylvia conmmunis en la Reserva de DoñanaSobre el lirón Gris (Glis glis pyrenaicus Cabrera, 1908) en España.Sobre alimentación y biología de la Gineta (Genetta genetta lo) en EspañaEliomys quercinus valverdei, un nuevo lirón careto del noroeste de la Península IbéricaPeer reviewe
AMPK is a mechano-metabolic sensor linking cell adhesion and mitochondrial dynamics to Myosin-dependent cell migration
Cell migration is crucial for cancer dissemination. We find that AMP-activated protein kinase (AMPK) controls cell migration by acting as an adhesion sensing molecular hub. In 3-dimensional matrices, fast-migrating amoeboid cancer cells exert low adhesion/low traction linked to low ATP/AMP, leading to AMPK activation. In turn, AMPK plays a dual role controlling mitochondrial dynamics and cytoskeletal remodelling. High AMPK activity in low adhering migratory cells, induces mitochondrial fission, resulting in lower oxidative phosphorylation and lower mitochondrial ATP. Concurrently, AMPK inactivates Myosin Phosphatase, increasing Myosin II-dependent amoeboid migration. Reducing adhesion or mitochondrial fusion or activating AMPK induces efficient rounded-amoeboid migration. AMPK inhibition suppresses metastatic potential of amoeboid cancer cells in vivo, while a mitochondrial/AMPK-driven switch is observed in regions of human tumours where amoeboid cells are disseminating. We unveil how mitochondrial dynamics control cell migration and suggest that AMPK is a mechano-metabolic sensor linking energetics and the cytoskeleton
Modernizing and Expanding the NASA Space Geodesy Network to Meet Future Geodetic Requirements
NASA maintains and operates a global network of Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Global Navigation Satellite System ground stations as part of the NASA Space Geodesy Program. The NASA Space Geodesy Network (NSGN) provides the geodetic products that support Earth observations and the related science requirements as outlined by the US National Research Council (NRC in Precise geodetic infrastructure: national requirements for a shared resource, National Academies Press, Washington, 2010. http://nap.edu/12954, Thriving on our changing planet: a decadal strategy for Earth observation from space, National Academies Press, Washington, 2018. http://nap.edu/24938). The Global Geodetic Observing System (GGOS) and the NRC have set an ambitious goal of improving the Terrestrial Reference Frame to have an accuracy of 1 mm and stability of 0.1 mm per year, an order of magnitude beyond current capabilities. NASA and its partners within GGOS are addressing this challenge by planning and implementing modern geodetic stations colocated at existing and new sites around the world. In 2013, NASA demonstrated the performance of its next-generation systems at the prototype next-generation core site at NASAs Goddard Geophysical and Astronomical Observatory in Greenbelt, Maryland. Implementation of a new broadband VLBI station in Hawaii was completed in 2016. NASA is currently implementing new VLBI and SLR stations in Texas and is planning the replacement of its other aging domestic and international legacy stations. In this article, we describe critical gaps in the current global network and discuss how the new NSGN will expand the global geodetic coverage and ultimately improve the geodetic products. We also describe the characteristics of a modern NSGN site and the capabilities of the next-generation NASA SLR and VLBI systems. Finally, we outline the plans for efficiently operating the NSGN by centralizing and automating the operations of the new geodetic stations
Revista de Vertebrados de la Estación Biológica de Doñana
Clave preliminar de las escamas de los peces de agua dulce de España, a nivel de familiaExito reproductor del Buitre leonado (Gyps fulvus) en NavarraAlimentación del Gavilán (Accipiter nisus) en la Isla de TenerifeEl Verdecillo (Serinus serinus): Tendencias en la estación de nidificación, en el tamaño del huevo y en la supervivencia.las batidas como método de censo en especiesde caza mayor: aplicación al caso del Jabalí (Sus scrofa L.) en la provincia de Burgos (Norte de España)La adquisición de madurez sexual en el camaleón común (Chamaeleo chamaeleon)Nuevas citas de Hemidactylus turcicus en la provincia de CáceresLa focha común (Fulica atra) en la isla de Gran Canaria: nueva especie nidificante en el archipiélago CanarioTraslado de huevos en incubación por la urraca (Pica pica)Predación de Falco peregrinus sobre Oryctolagus cuniculusCuatro nuevas especies de aves para Bolivia.Sobre la utilización de nidos de golondrina común abandonados.Parasitismo múltiple del críalo (Clamator glandarius)Predación del topo de rio (Galemys pyrenaicus, Geoffroy 1811) por parte de la lechuza común (Tyto alba, Scopoli 1769)Predación del zorro (Vulpes vulpes) sobre un pollo de buitre leonado (Gyps fulvus).Vulpes vulpes L. criando en una colonia de marmota (Marmota marmota L.) en el pirineo de LéridaObservaciones sobre la incidencia de Rattus (Fischer, 1803) en los cultivos ibéricos de caña de azúcaSituación actual de la jutiita de la tierra Capromys sanfelipensis (Rodentia, Mammalia)Notas sobre la intraducción y expansión de la ardilla común en Sierra Nevada, sureste de EspañaPeer reviewe
Global CO2 emissions from dry inland waters share common drivers across ecosystems
©. This manuscript version is made available under the CC BY 4.0 license http://creativecommons.org/licenses/ccby/4.0/
This document is the Published, version of a Published Work that appeared in final form in [Nature communications]. To access the final edited and published work see [https://doi.org/.1038/s41467-020-15929-y]Many inland waters exhibit complete or partial desiccation, or have vanished due to global
change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions
from these sediments are too scarce to upscale emissions for global estimates or to
understand their fundamental drivers. Here, we present the results of a global survey covering
196 dry inland waters across diverse ecosystem types and climate zones. We show that
their CO2 emissions share fundamental drivers and constitute a substantial fraction of the
carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and
climate zones, with local characteristics explaining much of the variability. Accounting for
such emissions increases global estimates of carbon emissions from inland waters by 6%
(~0.12 Pg C y−1). Our results indicate that emissions from dry inland waters represent a
significant and likely increasing component of the inland waters carbon cycle
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