3,771 research outputs found
Fertilizer Placement and Tillage Interaction in Corn and Soybean Production
Different tillage systems can affect the availability of phosphorus (P) by changing the soil environment. The objective of this study was to evaluate the effects and interaction of fertilizer placement, tillage, and varieties for soybean and corn. The experiment was established at two locations in Kansas in 2014. The experimental design was a factorial in a randomized complete block with four replications. Three fertilizer treatments were combined with two tillage systems and two varieties of soybean and corn selected based on contrasting root systems. Plant tissue samples were collected during the vegetative and reproductive stages to evaluate P concentration, P uptake, and dry matter. Significant differences were found in the parameters across locations for corn and soybean. Results suggest advantages for deep-band application for soybean and broadcast application for corn. Varieties responded differently in the parameters evaluated in this study
Grain Sorghum Response to Band Applied Zinc Fertilizer
Zinc (Zn) is one of the micronutrients found to be deficient in Kansas. The objective of this study was to evaluate the response of grain sorghum to Zn fertilization using strip trials. The experiment was set up in Manhattan, KS, in 2015. The experimental design consisted of two strips, one with Zn fertilizer and the other without, with five replications. Zn fertilizer was applied as starter in combination with ammonium polyphosphate at the rate of 0.5 lb Zn/a. Plant tissue samples were collected to determine Zn content. Grain yield was recorded by combine equipped with yield monitor. No significant differences were found for sorghum grain yield. Grain Zn content increased with Zn fertilization. Zn fertilization may be considered for future studies in food biofortification
Ecopedagogía para la formación bioética ambiental en estudiantes de enfermería
It is urgent to become aware to restore and protect the environment, due to the magnitude of environmental destruction worldwide that human beings have produced by allowing themselves to be carried away by a culture of consumerism and waste, without considering the future consequences for the next generations. . The environment is considered a determinant of health, therefore it is important to incorporate it in the study of nursing professionals, being pertinent to use the principles of eco-pedagogy during their training since it focuses not only on environmental education, but also includes the vision of sustainable development, that is, taking care of the environment and making reasonable use of it to improve people's living conditions. This essay aims to reflect on and analyze the importance of eco-pedagogy for the training in environmental bioethics of future nursing professionals.Es urgente tomar conciencia para restablecer y proteger el ambiente, debido a la magnitud de la destrucción ambiental a nivel mundial que ha producido el propio ser humano al dejarse llevar por una cultura de consumismo y descarte, sin considerar las consecuencias a futuro para las próximas generaciones. El ambiente es considerado un determinante de la salud, por ello es importante incorporarlo en el estudio de los profesionales de enfermería, siendo pertinente utilizar los principios de la ecopedagogía durante su formación puesto que se enfoca no solo en la educación ambiental, sino que incluye la visión de desarrollo sostenible, es decir cuidar el ambiente y aprovecharlo de manera razonable, para mejorar las condiciones de vida de las personas. Con este ensayo se pretende reflexionar y analizar la importancia de la ecopedagogía para la formación en bioética ambiental de los futuros profesionales de enfermería
The Nuclear and Circum-nuclear Stellar Population in Seyfert 2 Galaxies: Implications for the Starburst-AGN Connection
We report the results of a spectroscopic investigation of a sample of 20 of
the brightest type 2 Seyfert nuclei. Our goal is to search for the direct
spectroscopic signature of massive stars, and thereby probe the role of
circumnuclear starbursts in the Seyfert phenomenon. The method used is based on
the detection of the higher order Balmer lines and HeI lines in absorption and
the Wolf-Rayet feature at 4680 \AA in emission. These lines are strong
indicators of the presence of young (a few Myrs) and intermediate-age (a few
100 Myrs) stellar populations. In over half the sample, we have detected HeI
and/or strong stellar absorption features in the high-order (near-UV) Balmer
series together with relatively weak lines from an old stellar population. In
three others we detect a broad emission feature near 4680 \AA that is most
plausibly ascribed to a population of Wolf-Rayet stars (the evolved descendants
of the most massive stars). We therefore conclude that the blue and near-UV
light of over half of the sample is dominated by young and/or intermediate age
stars. The ``young'' Seyfert 2's have have larger far-IR luminosities, cooler
mid/far-IR colors, and smaller [OIII]/H flux ratios than the ``old''
ones. These differences are consistent with a starburst playing a significant
energetic role in the former class. We consider the possibility that there may
be two distinct sub-classes of Seyfert 2 nuclei (``starbursts'' and ``hidden
BLR''). However, the fact that hidden BLRs have been found in three of the
``young'' nuclei argues against this, and suggests that nuclear starbursts may
be a more general part of the Seyfert phenomenon.Comment: To be published in ApJ, 546, Jan 10, 200
Multiwavelength study of the starburst galaxy NGC7714. I: Ultraviolet-Optical spectroscopy
We have studied the physical conditions in the central 300 pc of the
proto-typical starburst galaxy NGC 7714. Our analysis is based on ultraviolet
spectroscopy with the HST+GHRS and ground-based optical observations.The data
are interpreted using evolutionary models optimized for young starburst
regions. The massive stellar population is derived in a self-consistent way
using the continuum and stellar absorption lines in the ultraviolet and the
nebular emission line optical spectrum.
The central starburst has an age of about 4.5 Myr, with little evidence for
an age spread. Wolf-Rayet features at the ultraviolet indicates a stellar
population of 2000 Wolf-Rayet stars. The overall properties of the newly
formed stars are quite similar to those derived, e.g., in 30 Doradus. A
standard Salpeter IMF is consistent with all observational constraints. We find
evidence for spatial structure within the central 300 pc sampled. Therefore it
is unlikely that the nucleus of NGC 7714 hosts a single star cluster exceeding
the properties of other known clusters. Contrary to previous suggestions, we
find no evidence for a nuclear supernova rate that would significantly exceed
the total disk-integrated rate. About one supernova event per century is
predicted.Comment: 19 pages, 9 figures in a tar file. Accepted for publication in ApJ,
1999, March, issue 51
The Structure and Star-Formation History of NGC 5461
We compute photoionization models for the giant extragalactic H II region NGC
5461, and compare their predictions to several observational constraints. Since
we aim at reproducing not only the global properties of the region, but its
local structure also, the models are constrained to reproduce the observed
density profile, and our analysis takes into consideration the bias introduced
by the shapes and sizes of the slits used by different observers. We find that
an asymmetric nebula with a gaussian density distribution, powered by a young
burst of 3.1 Myr, satisfactorily reproduces most of the constraints, and that
the star-formation efficiency inferred from the model agrees with current
estimates. Our results strongly depend on the assumed density law, since
constant density models overestimate the hardness of the ionizing field,
affecting the deduced properties of the central stellar cluster. We illustrate
the features of our best model, and discuss the possible sources of errors and
uncertainties affecting the outcome of this type of studies.Comment: 33 pages (LaTeX), 3 .eps figures. to be published in ApJ, May 200
The nuclear receptor LXRα controls the functional specialization of splenic macrophages.
Macrophages are professional phagocytic cells that orchestrate innate immune responses and have considerable phenotypic diversity at different anatomical locations. However, the mechanisms that control the heterogeneity of tissue macrophages are not well characterized. Here we found that the nuclear receptor LXRα was essential for the differentiation of macrophages in the marginal zone (MZ) of the spleen. LXR-deficient mice were defective in the generation of MZ and metallophilic macrophages, which resulted in abnormal responses to blood-borne antigens. Myeloid-specific expression of LXRα or adoptive transfer of wild-type monocytes restored the MZ microenvironment in LXRα-deficient mice. Our results demonstrate that signaling via LXRα in myeloid cells is crucial for the generation of splenic MZ macrophages and identify an unprecedented role for a nuclear receptor in the generation of specialized macrophage subsets
Carbon in Spiral Galaxies from Hubble Space Telescope Spectroscopy
We present measurements of the gas-phase C/O abundance ratio in six H II
regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet
spectroscopy using the Faint Object Spectrograph on the Hubble Space Telescope.
The C/O ratios increase systematically with O/H in both galaxies, from log C/O
approximately -0.8 at log O/H = -4.0 to log C/O approx. -0.1 at log O/H = -3.4.
C/N shows no correlation with O/H. The rate of increase of C/O is somewhat
uncertain because of uncertainty as to the appropriate UV reddening law, and
uncertainty in the metallicity dependence on grain depletions. However, the
trend of increasing C/O with O/H is clear, confirming and extending the trend
in C/O indicated previously from observations of irregular galaxies. Our data
indicate that the radial gradients in C/H across spiral galaxies are steeper
than the gradients in O/H. Comparing the data to chemical evolution models for
spiral galaxies shows that models in which the massive star yields do not vary
with metallicity predict radial C/O gradients that are much flatter than the
observed gradients. The most likely hypothesis at present is that stellar winds
in massive stars have an important effect on the yields and thus on the
evolution of carbon and oxygen abundances. C/O and N/O abundance ratios in the
outer disks of spirals determined to date are very similar to those in dwarf
irregular galaxies. This implies that the outer disks of spirals have average
stellar population ages much younger than the inner disks.Comment: 38 pages, 9 postscript figures, uses aaspp4.sty. Accepted for
publication in The Astrophysical Journa
The Arabidopsis thioredoxin TRXh5regulates the S-nitrosylation pattern of the TIRK receptor being both proteins essential in the modulation of defences to Tetranychus urticae
The interaction between plants and phytophagous arthropods encompasses a complex network of molecules, signals, and pathways to overcome defences generated by each interacting organism. Although most of the elements and modulators involved in this interplay are still unidentified, plant redox homeostasis and signalling are essential for the establishment of defence responses. Here, focusing on the response of Arabidopsis thaliana to the spider mite Tetranychus urticae, we demonstrate the involvement in plant defence of the thioredoxin TRXh5, a small redox protein whose expression is induced by mite infestation. TRXh5 is localized in the cell membrane system and cytoplasm and is associated with alterations in the content of reactive oxygen and nitrogen species. Protein S-nitrosylation signal in TRXh5 over-expression lines is decreased and alteration in TRXh5 level produces changes in the JA/SA hormonal crosstalk of infested plants. Moreover, TRXh5 interacts and likely regulates the redox state of an uncharacterized receptor-like kinase, named THIOREDOXIN INTERACTING RECEPTOR KINASE (TIRK), also induced by mite herbivory. Feeding bioassays performed withTRXh5 over-expression plants result in lower leaf damage and reduced egg accumulation after T. urticae infestation than in wild-type (WT) plants. In contrast, mites cause a more severe injury in trxh5 mutant lines where a greater number of eggs accumulates. Likewise, analysis of TIRK-gain and -loss-of-function lines demonstrate the defence role of this receptor in Arabidopsis against T. urticae. Altogether, our findings demonstrate the interaction between TRXh5 and TIRK and highlight the importance of TRXh5 and TIRK in the establishment of effective Arabidopsis defences against spider mite herbivory.Grants PID2020-115219RB-I00, RED2018-102397-T and RyC17MESFB funded by MCIN/AEI/10.13039/501100011033, as appropriate, by “ERDF A way of making Europe” and by the “European Union” supported this work. Grants, SIMQG-263-1HWZ8Q UPM-Banco Santander Universidades, RyC2017-21814 and PRE2018-083375 from MCIN/AEI supported AA, MES and IRD, respectively. The Spanish Ministry of Science and Innovation (MCIN), the State Research Agency (AEI) and the European Regional Development Fund (ERDF; grant MEC-PID2021-122280NB-I00) financed MCRP and LMS. The Government of Canada through the Ontario Research Fund (RE08-067) and the Natural Sciences and Engineering Research Council of Canada (NSERC, RGPIB-2018-04538) supported VG
- …