1,315 research outputs found
Fish seed production in ricefields: participatory training and extension manual
Seed (aquaculture), Rice field aquaculture, Rice fields, Manuals Oreochromis niloticus
Dynamics of Sclerotium rolfsii as influenced by different crop rhizosphere and microbial community
This study was carried out with the aim of evaluating pathogenicity of Sclerotium rolfsii to different crops influenced by different crop rhizosphere microbes and their population dynamics. Napier was found to be non-preferred host against S. rolfsii pathogen. Among the seven tested crops in micro-plot study, highest level of induction of sclerotial population was observed in groundnut and cow peas (21.81 and 20.06 numbers of sclerotia /100 g of soil, respectively), whereas, reduction in sclerotial number was observed in napier, maize and sorghum plots. S. rolfsii induced damping off was found to be significantly positively correlated with average sclerotial population irrespective of plant cover even at 1% level of significance (r = 0.985) and among the microbiological parameters, FDA was found to be significantly negatively correlated with damping off disease percentage at 5% level of significance (r = - 0.830). Therefore, Napier may be the potential crop to be incorporated in the sequence of rice/vegetable based cropping system in West Bengal for management of this dreaded pathogen
Comment on low-temperature transport properties of non-stoichiometric La_{0.95-x}Sr_{x}MnO_{3}
In a recent paper (Michalopolou A., Syskakis E. and Papastaikoudis C., 2001
J. Phys.: Cond. Mat. 13, 11615) the authors reported on the measurements of
electrical resistivity and specific heat at zero magnetic field carried out on
polycrystalline non-stoichiometric La_{0.95-x}Sr_{x}MnO_{3} manganites.In
particular, they attributed the low temperature behavior of resistivity
(shallow minimum and slight upturn at lowest temperatures) to 3D
electron-electron interaction enhanced by disorder, using results of numerical
fittings of the dependencies of resistivity on temperature in the interval 4.2
-- 40 K. We argue that such an analysis may be not valid for polycrystalline
manganites where relatively strong grain boundary effects might mask weak
contribution of quantum effects to low temperature resistivity. The crucial
test of applicability of the theory of quantum corrections to conductivity in
this case is the resistive measurements under non-zero magnetic field.Comment: pdf, 6 pages, submitted to J. Phys.: Cond. Matte
A Molecular CO2 Reduction Catalyst Based on Giant Polyoxometalate {Mo368}
Photocatalytic CO2 reduction in water is one of the most attractive research pursuits of our time. In this article we report a giant polyoxometalate {Mo368} based homogeneous catalytic system, which efficiently reduces CO2 to formic acid with a maximum turnover number (TON) of 27,666, turnover frequency (TOF) of 4,611 h−1 and external quantum efficiency of the reaction is 0.6%. The catalytic system oxidizes water and releases electrons, and these electrons are further utilized for the reduction of CO2 to formic acid. A maximum of 8.3 mmol of formic acid was observed with the loading of 0.3 μmol of the catalyst. Our catalyst material is also stable throughout the reaction. The starting materials for this experiment are CO2 and H2O and the end products are HCOOH and O2. The formic acid formed in this reaction is an important H2 gas carrier and thus significant in renewable energy research
Positive Outcomes of Human Resources Engagement and Impact on Motivation
For this study, I don’t intend to show teachers as victims of their school, nor that Human
Resources is the only problem that needs to be fixed or that our education system is the issue.
We only intended to question why teachers are always blamed, and their needs are ignored
and always accused them of being demotivated. We mean to question how the education
system functions with the lack of Human Resources practices and the methods and ideas that
we can provide and help our teachers have a better future. We intend to discover what the best
way to motivate and engage teachers through Human Resources practices is. What makes the
admins dissatisfied with teachers’ performance, and is it the fault of the teachers. This study is
a series of concerns and problems teachers (including ourselves) came across through our
teaching years that nobody ever tried to see it from our point of view. This article is a group of
chains and ideas that will give more value to teachers and encourage Human Resources to be
more engaged and active in teachers lives through many methods and techniques.
Furthermore, teachers’ demotivation and lack of engagement are causing burnouts and
turnovers; we’ll try to show how Human Resources can help reduce these turnovers and burnouts through being more present and implement motivational systems and engagement
models. This article will review previous literature related to Human Resources engagement
and motivation positivity on teachers’ performance and productivity. It will discuss these
demotivating factors and assess their impact on teachers’ performance and end with. This
article will conclude by implementing more motivational and engagement systems and
programs to enhance teachers performance, reduce turnovers, and make schools a better
environment for students
Cationic vacancy induced room-temperature ferromagnetism in transparent conducting anatase Ti_{1-x}Ta_xO_2 (x~0.05) thin films
We report room-temperature ferromagnetism in highly conducting transparent
anatase Ti1-xTaxO2 (x~0.05) thin films grown by pulsed laser deposition on
LaAlO3 substrates. Rutherford backscattering spectrometry (RBS), x-ray
diffraction (XRD), proton induced x-ray emission (PIXE), x-ray absorption
spectroscopy (XAS) and time-of-flight secondary ion mass spectrometry
(TOF-SIMS) indicated negligible magnetic contaminants in the films. The
presence of ferromagnetism with concomitant large carrier densities was
determined by a combination of superconducting quantum interference device
(SQUID) magnetometry, electrical transport measurements, soft x-ray magnetic
circular dichroism (SXMCD), XAS, and optical magnetic circular dichroism (OMCD)
and was supported by first-principle calculations. SXMCD and XAS measurements
revealed a 90% contribution to ferromagnetism from the Ti ions and a 10%
contribution from the O ions. RBS/channelling measurements show complete Ta
substitution in the Ti sites though carrier activation was only 50% at 5% Ta
concentration implying compensation by cationic defects. The role of Ti vacancy
and Ti3+ was studied via XAS and x-ray photoemission spectroscopy (XPS)
respectively. It was found that in films with strong ferromagnetism, the Ti
vacancy signal was strong while Ti3+ signal was absent. We propose (in the
absence of any obvious exchange mechanisms) that the localised magnetic
moments, Ti vacancy sites, are ferromagnetically ordered by itinerant carriers.
Cationic-defect-induced magnetism is an alternative route to ferromagnetism in
wide-band-gap semiconducting oxides without any magnetic elements.Comment: 21 pages, 10 figures, to appear in Philosophical Transaction - Royal
Soc.
230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Costa, K. M., Hayes, C. T., Anderson, R. F., Pavia, F. J., Bausch, A., Deng, F., Dutay, J., Geibert, W., Heinze, C., Henderson, G., Hillaire-Marcel, C., Hoffmann, S., Jaccard, S. L., Jacobel, A. W., Kienast, S. S., Kipp, L., Lerner, P., Lippold, J., Lund, D., Marcantonio, F., McGee, D., McManus, J. F., Mekik, F., Middleton, J. L., Missiaen, L., Not, C., Pichat, S., Robinson, L. F., Rowland, G. H., Roy-Barman, M., Alessandro, Torfstein, A., Winckler, G., & Zhou, Y. 230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean. Paleoceanography and Paleoclimatology, 35(2), (2020): e2019PA003820, doi:10.1029/2019PA003820.230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).We thank Zanna Chase and one anonymous reviewer for valuable feedback. K. M. C. was supported by a Postdoctoral Scholarship at WHOI. L. M. acknowledges funding from the Australian Research Council grant DP180100048. The contribution of C. T. H., J. F. M., and R. F. A. were supported in part by the U.S. National Science Foundation (US‐NSF). G. H. R. was supported by the Natural Environment Research Council (grant NE/L002434/1). S. L. J. acknowledges support from the Swiss National Science Foundation (grants PP002P2_144811 and PP00P2_172915). This study was supported by the Past Global Changes (PAGES) project, which in turn received support from the Swiss Academy of Sciences and the US‐NSF. This work grew out of a 2018 workshop in Aix‐Marseille, France, funded by PAGES, GEOTRACES, SCOR, US‐NSF, Aix‐Marseille Université, and John Cantle Scientific. All data are publicly available as supporting information to this document and on the National Center for Environmental Information (NCEI) at https://www.ncdc.noaa.gov/paleo/study/28791
Nonlinear Insulator in Complex Oxides
The insulating state is one of the most basic electronic phases in condensed
matter. This state is characterised by an energy gap for electronic excitations
that makes an insulator electrically inert at low energy. However, for complex
oxides, the very concept of an insulator must be re-examined. Complex oxides
behave differently from conventional insulators such as SiO2, on which the
entire semiconductor industry is based, because of the presence of multiple
defect levels within their band gap. As the semiconductor industry is moving to
such oxides for high-dielectric (high-k) materials, we need to truly understand
the insulating properties of these oxides under various electric field
excitations. Here we report a new class of material called nonlinear insulators
that exhibits a reversible electric-field-induced metal-insulator transition.
We demonstrate this behaviour for an insulating LaAlO3 thin film in a
metal/LaAlO3/Nb-SrTiO3 heterostructure. Reproducible transitions were observed
between a low-resistance metallic state and a high-resistance non-metallic
state when applying suitable voltages. Our experimental results exclude the
possibility that diffusion of the metal electrodes or oxygen vacancies into the
LaAlO3 layer is occurring. Instead, the phenomenon is attributed to the
formation of a quasi-conduction band (QCB) in the defect states of LaAlO3 that
forms a continuum state with the conduction band of the Nb-SrTiO3. Once this
continuum (metallic) state is formed, the state remains stable even when the
voltage bias is turned off. An opposing voltage is required to deplete the
charges from the defect states. Our ability to manipulate and control these
defect states and, thus, the nonlinear insulating properties of complex oxides
will open up a new path to develop novel devices.Comment: 23 pages, 4 figure
Sulfide melts and long-term low seismic wavespeeds in lithospheric and asthenospheric mantle
Some studies of lithospheric and asthenospheric seismic structure, report mantle velocities as low as ∼4% below the reference models used. While these low wavespeeds may be attributed to thermal effects in tectonically young or actively volcanic regions, in older, tectonically stable regions low velocity anomalies apparently persist even past the decay time of any thermal perturbation, rendering such a mechanism implausible. Low volume melts can also reduce wavespeeds, but their buoyancy should drain them upward away from source regions, preventing significant accumulation if they are able to segregate. Sulfide, ubiquitous as inclusions in lithospheric mantle xenoliths, forms dense, non-segregating melts at temperatures and volatile fugacities characteristic of even old lithospheric mantle. We show that 1–5 volume percent sulfide melts can act to permanently create reductions up to 5.5% in seismic wavespeeds in areas of the lithosphere and the asthenosphere disturbed by prior melting events that carry and concentrate sulfide
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