266 research outputs found
Combined Norepinephrine/Serotonergic Reuptake Inhibition: Effects on Maternal Behavior, Aggression, and Oxytocin in the Rat
Background: Few systematic studies exist on the effects of chronic reuptake of monoamine neurotransmitter systems during pregnancy on the regulation of maternal behavior (MB), although many drugs act primarily through one or more of these systems. Previous studies examining fluoxetine and amfonelic acid treatment during gestation on subsequent MB in rodents indicated significant alterations in postpartum maternal care, aggression, and oxytocin levels. In this study, we extended our studies to include chronic gestational treatment with desipramine or amitriptyline to examine differential effects of reuptake inhibition of norepinephrine and combined noradrenergic and serotonergic systems on MB, aggression, and oxytocin system changes. Methods: Pregnant Sprague-Dawley rats were treated throughout gestation with saline or one of three doses of either desipramine, which has a high affinity for the norepinephrine monoamine transporter, or amitriptyline, an agent with high affinity for both the norepinephrine and serotonin monoamine transporters. MB and postpartum aggression were assessed on postpartum days 1 and 6 respectively. Oxytocin levels were measured in relevant brain regions on postpartum day 7. Predictions were that amitriptyline would decrease MB and increase aggression relative to desipramine, particularly at higher doses. Amygdaloidal oxytocin was expected to decrease with increased aggression. Results: Amitriptyline and desipramine differentially reduced MB, and at higher doses reduced aggressive behavior. Hippocampal oxytocin levels were lower after treatment with either drug but were not correlated with specific behavioral effects. These results, in combination with previous findings following gestational treatment with other selective neurotransmitter reuptake inhibitors, highlight the diverse effects of multiple monoamine systems thought to be involved in maternal care
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Potential for early forecast of Moroccan wheat yields based on climatic drivers
Wheat production plays an important role in Morocco. Current wheat forecast systems use weather and vegetation data during the crop growing phase, thus limiting the earliest possible release date to early spring. However, Morocco' s wheat production is mostly rainfed and thus strongly tied to fluctuations in rainfall, which in turn depend on slowly evolving climate dynamics. This offers a source of predictability at longer time scales. Using physically guided causal discovery algorithms, we extract climate precursors for wheat yield variability from gridded fields of geopotential height and sea surface temperatures which show potential for accurate yield forecasts already in December, with around 50% explained variance in an out‐of‐sample cross validation. The detected interactions are physically meaningful and consistent with documented ocean‐atmosphere feedbacks. Reliable yield forecasts at such long lead times could provide farmers and policy makers with necessary information for early action and strategic adaptation measurements to support food security
Thermohaline mixing and the photospheric composition of low-mass giant stars
We compute full evolutionary sequences of red giant branch stars close to the
luminosity bump by including state of the art composition transport
prescriptions for the thermohaline mixing regimes. In particular we adopt a
self-consistent double-diffusive convection theory, that allows to handle the
instabilities that arise when thermal and composition gradients compete against
each other, and a very recent empirically motivated and parameter free
asymptotic scaling law for thermohaline composition transport. In agreement
with previous works, we find that during the red giant stage, a thermohaline
instability sets in shortly after the hydrogen burning shell (HBS) encounters
the chemical discontinuity left behind by the first dredge-up. We also find
that the thermohaline unstable region, initially appearing at the exterior wing
of the HBS, is unable to reach the outer convective envelope, with the
consequence that no mixing of elements that produces a non-canonical
modification of the stellar surface abundances occurs. Also in agreement with
previous works, we find that by artificially increasing the mixing efficiency
of thermohaline regions it is possible to connect both unstable regions, thus
affecting the photospheric composition. However, we find that in order to
reproduce the observed abundances of red giant branch stars close to the
luminosity bump, thermohaline mixing efficiency has to be artificially
increased by about 4 orders of magnitude from that predicted by recent 3D
numerical simulations of thermohaline convection close to astrophysical
environments. From this we conclude the chemical abundance anomalies of red
giant stars cannot be explained on the basis of thermohaline mixing alone.Comment: 7 pages, 6 figures, accepted for publication in A&
Repetition and difference: Lefebvre, Le Corbusier and modernity's (im)moral landscape: a commentary
This article engages with the relationship between social theory, architectural theory and material culture. The article is a reply to an article in a previous volume of the journal in question (Smith, M. (2001) ‘Repetition and difference: Lefebvre, Le Corbusier and modernity’s (im)moral landscape’, Ethics, Place and Environment, 4(1), 31-34) and, consequently, is also a direct engagement with another academic's scholarship. It represents a critique of their work as well as a recasting of their ideas, arguing that the matter in question went beyond interpretative issues to a direct critique of another author's scholarship on both Le Corbusier and Lefebvre. A reply to my article from the author of the original article was carried in a later issue of the journal (Smith, M. (2002) ‘Ethical Difference(s): a Response to Maycroft on Le Corbusier and Lefebvre’, Ethics, Place and Environment, 5(3), 260-269)
Thermohaline mixing in evolved low-mass stars
Thermohaline mixing has recently been proposed to occur in low-mass red
giants, with large consequence for the chemical yields of low-mass stars. We
investigate the role of thermohaline mixing during the evolution of stars
between 1Msun and 3Msun, in comparison to other mixing processes acting in
these stars. We use a stellar evolution code which includes rotational mixing,
internal magnetic fields and thermohaline mixing. We confirm that during the
red giant stage, thermohaline mixing has the potential to decrease the
abundance of ^3He which is produced earlier on the main sequence. In our models
we find that this process is working on the RGB only in stars with initial mass
M \simle 1.5Msun. Moreover we report that thermohaline mixing is present also
during core helium burning and beyond, and has the potential to change the
surface abundances of AGB stars. While we find rotational and magnetic mixing
to be negligible compared to the thermohaline mixing in the relevant layers,
the interaction of thermohaline motions with the differential rotation may be
essential to establish the time scale of thermohaline mixing in red giants. To
explain the surface abundances observed at the bump in the luminosity function,
the speed of the mixing process needs to be more than two orders of magnitude
higher than in our models. However it is not clear if thermohaline mixing is
the only physical process responsible for these surface abundance anomalies.
Therefore, at this stage, it is not possible to calibrate the efficiency of
thermohaline mixing against the observations.Comment: 10 pages - Accepted for publication in A&
The Climate-system Historical Forecast Project: providing open access to seasonal forecast ensembles from centers around the globe
Fil: Tompkins, Adrian M.. The Abdus Salam; ItaliaFil: Ortiz de Zarate, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Saurral, Ramiro Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Vera, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Merryfield, William J.. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Sigmond, Michael. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Lee, Woo Sung. Canadian Centre for Climate Modelling and Analysis; CanadáFil: Baehr, Johanna. Universitat Hamburg; AlemaniaFil: Braun, Alain. Météo-France; FranciaFil: Amy Butler. National Ocean And Atmospheric Administration; Estados UnidosFil: Déqué, Michel. Météo-France; FranciaFil: Doblas Reyes, Francisco J.. Institució Catalana de Recerca i Estudis Avancats; España. Barcelona Supercomputing Center - Centro Nacional de Supercomputacion; EspañaFil: Gordon, Margaret. Met Office; Reino UnidoFil: Scaife, Adam A.. University of Exeter; Reino UnidoFil: Yukiko Imada. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Masayoshi Ishii. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Tomoaki Ose. Japan Meteorological Agency. Meteorological Research Institute. Climate Research Department; JapónFil: Kirtman, Ben. University of Miami; Estados UnidosFil: Kumar, Arun. National Ocean And Atmospheric Administration; Estados UnidosFil: Müller, Wolfgang A.. Max-Planck-Institut für Meteorologie; AlemaniaFil: Pirani, Anna. Université Paris-Saclay; FranciaFil: Stockdale, Tim. European Centre for Medium-Range Weather; Reino UnidoFil: Rixen, Michel. World Meteorological Organization. World Climate Research Programme; SuizaFil: Yasuda, Tamaki. Japan Meteorological Agency. Climate Prediction Division; Japó
Presupernova Structure of Massive Stars
Issues concerning the structure and evolution of core collapse progenitor
stars are discussed with an emphasis on interior evolution. We describe a
program designed to investigate the transport and mixing processes associated
with stellar turbulence, arguably the greatest source of uncertainty in
progenitor structure, besides mass loss, at the time of core collapse. An
effort to use precision observations of stellar parameters to constrain
theoretical modeling is also described.Comment: Proceedings for invited talk at High Energy Density Laboratory
Astrophysics conference, Caltech, March 2010. Special issue of Astrophysics
and Space Science, submitted for peer review: 7 pages, 3 figure
Robust skill of decadal climate predictions
There is a growing need for skilful predictions of climate up to a decade ahead. Decadal climate predictions show high skill for surface temperature, but confidence in forecasts of precipitation and atmospheric circulation is much lower. Recent advances in seasonal and annual prediction show that the signal-to-noise ratio can be too small in climate models, requiring a very large ensemble to extract the predictable signal. Here, we reassess decadal prediction skill using a much larger ensemble than previously available, and reveal significant skill for precipitation over land and atmospheric circulation, in addition to surface temperature. We further propose a more powerful approach than used previously to evaluate the benefit of initialisation with observations, improving our understanding of the sources of skill. Our results show that decadal climate is more predictable than previously thought and will aid society to prepare for, and adapt to, ongoing climate variability and change.D.M.S., A.A.S., N.J.D., L.H. and R.E. were supported by the Met Office Hadley Centre
Climate Programme funded by BEIS and Defra and by the European Commission
Horizon 2020 EUCP project (GA 776613). L.P.C. was supported by the Spanish
MINECO HIATUS (CGL2015-70353-R) project. F.J.D.R. was supported by the H2020
EUCP (GA 776613) and the Spanish MINECO CLINSA (CGL2017-85791-R) projects. W.A.
M. and H.P. were supported by the German Ministry of Education and Research
(BMBF) under the project MiKlip (grant 01LP1519A). The NCAR contribution was
supported by the US National Oceanic and Atmospheric Administration (NOAA)
Climate Program Office under Climate Variability and Predictability Program Grant
NA13OAR4310138 and by the US National Science Foundation (NSF) Collaborative
Research EaSM2 Grant OCE-1243015. The NCAR contribution is also based upon work
supported by NCAR, which is a major facility sponsored by the US NSF under
Cooperative Agreement No. 1852977. The Community Earth System Model Decadal
Prediction Large Ensemble (CESM-DPLE) was generated using computational
resources provided by the US National Energy Research Scientific Computing Center,
which is supported by the Office of Science of the US Department of Energy under
Contract DE-AC02-05CH11231, as well as by an Accelerated Scientific Discovery grant
for Cheyenne (https://doi.org/10.5065/D6RX99HX) that was awarded by NCAR’s
Computational and Information System Laboratory.Peer ReviewedPostprint (published version
Constraining mixing processes in stellar cores using asteroseismology. Impact of semiconvection in low-mass stars
The overall evolution of low-mass stars is heavily influenced by the
processes occurring in the stellar interior. In particular, mixing processes in
convectively unstable zones and overshooting regions affect the resulting
observables and main sequence lifetime. We study the effects of different
convective boundary definitions and mixing prescriptions in convective cores of
low-mass stars, to discriminate the existence, size, and evolutionary stage of
the central mixed zone by means of asteroseismology. We implemented the Ledoux
criterion for convection in our stellar evolution code, together with a
time-dependent diffusive approach for mixing of elements when semiconvective
zones are present. We compared models with masses ranging from 1 M* to 2 M*
computed with two different criteria for convective boundary definition and
including different mixing prescriptions within and beyond the formal limits of
the convective regions. Using calculations of adiabatic oscillations
frequencies for a large set of models, we developed an asteroseismic diagnosis
using only l=0 and l=1 modes based on the ratios of small to large separations
r01 and r10 defined by Roxburgh & Vorontsov (2003). These variables are almost
linear in the expected observable frequency range, and we show that their slope
depends simultaneously on the central hydrogen content, the extent of the
convective core, and the amplitude of the sound-speed discontinuity at the core
boundary. By considering about 25 modes and an accuracy in the frequency
determinations as expected from the CoRoT and Kepler missions, the technique we
propose allows us to detect the presence of a convective core and to
discriminate the different sizes of the homogeneously mixed central region
without the need of a strong a priori for the stellar mass.Comment: 13 pages, 9 figures, accepted for publication in A&
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