787 research outputs found
On periodic solutions of 2-periodic Lyness difference equations
We study the existence of periodic solutions of the non--autonomous periodic
Lyness' recurrence u_{n+2}=(a_n+u_{n+1})/u_n, where {a_n} is a cycle with
positive values a,b and with positive initial conditions. It is known that for
a=b=1 all the sequences generated by this recurrence are 5-periodic. We prove
that for each pair (a,b) different from (1,1) there are infinitely many initial
conditions giving rise to periodic sequences, and that the family of
recurrences have almost all the even periods. If a is not equal to b, then any
odd period, except 1, appears.Comment: 27 pages; 1 figur
Daphniid zooplankton assemblage shifts in response to eutrophication and metal contamination during the Anthropocene
Additional results from the principal component analyses conducted on eutrophication and metals data, as well as daphniid assemblages, and species richness rarefaction
Rpl33, a nonessential plastid-encoded ribosomal protein in tobacco, is required under cold stress conditions
Plastid genomes contain a conserved set of genes encoding components of the translational apparatus. While knockout of plastid translation is lethal in tobacco (Nicotiana tabacum), it is not known whether each individual component of the plastid ribosome is essential. Here, we used reverse genetics to test whether several plastid genome-encoded ribosomal proteins are essential. We found that, while ribosomal proteins Rps2, Rps4, and Rpl20 are essential for cell survival, knockout of the gene encoding ribosomal protein Rpl33 did not affect plant viability and growth under standard conditions. However, when plants were exposed to low temperature stress, recovery of Rpl33 knockout plants was severely compromised, indicating that Rpl33 is required for sustaining sufficient plastid translation capacity in the cold. These findings uncover an important role for plastid translation in plant tolerance to chilling stress
Desempenho de híbridos de milho no norte do Rio Grande do Sul.
O milho (Zea mays) apresenta benefícios na alimentação humana e animal, é o cereal mais cultivado no mundo, possuindo como ingrediente uma boa fonte energética
Avaliação de híbridos de milho no noroeste do Rio Grande do Sul safra 2019/2020.
O milho (Zea mays) é o cereal mais cultivado e consumido no mundo, devido ao seu elevado valor nutricional. O melhoramento do milho busca o desenvolvimento de cultivares adaptadas e com bom potencial produtivo
Ultrathin 2 nm gold as ideal impedance-matched absorber for infrared light
Thermal detectors are a cornerstone of infrared (IR) and terahertz (THz)
technology due to their broad spectral range. These detectors call for suitable
broad spectral absorbers with minimalthermal mass. Often this is realized by
plasmonic absorbers, which ensure a high absorptivity butonly for a narrow
spectral band. Alternativly, a common approach is based on impedance-matching
the sheet resistance of a thin metallic film to half the free-space impedance.
Thereby, it is possible to achieve a wavelength-independent absorptivity of up
to 50 %, depending on the dielectric properties of the underlying substrate.
However, existing absorber films typicallyrequire a thickness of the order of
tens of nanometers, such as titanium nitride (14 nm), whichcan significantly
deteriorate the response of a thermal transducers. Here, we present the
application of ultrathin gold (2 nm) on top of a 1.2 nm copper oxide seed layer
as an effective IR absorber. An almost wavelength-independent and long-time
stable absorptivity of 47(3) %, ranging from 2 m to 20 m, could be
obtained and is further discussed. The presented gold thin-film represents
analmost ideal impedance-matched IR absorber that allows a significant
improvement of state-of-the-art thermal detector technology
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