350 research outputs found
Broadly, independent-tunable, dual-wavelength mid-infrared ultrafast optical parametric oscillator
We demonstrate a two-crystal mid-infrared dual-wavelength optical parametric
oscillator, synchronously pumped by a high power femtosecond Yb:fiber laser.
The singly-resonant ring cavity, containing two periodically poled lithium
niobate crystals, is capable of generating two synchronized idler wavelengths,
independently tunable over 30 THz in the 2.9 - 4.2 {\mu}m wavelength region,
due to the cascaded quadratic nonlinear effect. The independent tunability of
the two idlers makes the optical parametric oscillator a promising source for
ultrafast pulse generation towards the THz wavelength region, based on
different frequency generation. In addition, the observed frequency doubled
idler within the crystal indicates the possibility to realize a broadband
optical self-phase locking between pump, signal, idler and higher order
generated parametric lights
Complexity and Inapproximability Results for Parallel Task Scheduling and Strip Packing
We study the Parallel Task Scheduling problem with a
constant number of machines. This problem is known to be strongly NP-complete
for each , while it is solvable in pseudo-polynomial time for each . We give a positive answer to the long-standing open question whether
this problem is strongly -complete for . As a second result, we
improve the lower bound of for approximating pseudo-polynomial
Strip Packing to . Since the best known approximation algorithm
for this problem has a ratio of , this result
narrows the gap between approximation ratio and inapproximability result by a
significant step. Both results are proven by a reduction from the strongly
-complete problem 3-Partition
Kajian Awal Dekteksi Dini Penyakit dalam dengan Metode Non-invasive Spektroskopi Fotoakustik Laser
Telah dilakukan kajian awal deteksi dini penyakit dalam menggunakan spektrometer fotoakustik (SFA) laser yang dibangun di Laboratorium Fisika Atom-Inti Jurusan Fisika FMIPA UGM. Eksperimen dilakukan dengan metode pengambilan sampel yang non-invasive yaitu melalui hembusan nafas relawan. Analisa data dari hasil eksperimen dilakukan menggunakan metode Analisis Multikoponen Gas dengan menggunakan software Origin dan Matlab. Hasil analisis dapat menunjukkan tiga macam gas karakteristik berbeda yang dapat dipakai untuk mencirikan suatu jenis penyakit tertentu, yaitu gas Etilen, Aseton dan Amonia.
Kata kunci: Fotoakustik laser dan Analisis multikomponen ga
Time-resolved mid-infrared dual-comb spectroscopy
Dual-comb spectroscopy can provide broad spectral bandwidth and high spectral
resolution in a short acquisition time, enabling time-resolved measurements.
Specifically, spectroscopy in the mid-infrared wavelength range is of
particular interest, since most of the molecules have their strongest
rotational-vibrational transitions in this "fingerprint" region. Here we report
time-resolved mid-infrared dual-comb spectroscopy for the first time, covering
~300 nm bandwidth around 3.3 {\mu}m with 6 GHz spectral resolution and 20
{\mu}s temporal resolution. As a demonstration, we study a CH4/He gas mixture
in an electric discharge, while the discharge is modulated between dark and
glow regimes. We simultaneously monitor the production of C2H6 and the
vibrational excitation of CH4 molecules, observing the dynamics of both
processes. This approach to broadband, high-resolution, and time-resolved
mid-infrared spectroscopy provides a new tool for monitoring the kinetics of
fast chemical reactions, with potential applications in various fields such as
physical chemistry and plasma/combustion analysis.Comment: 21 page, 6 figure
ABA Suppresses Botrytis cinerea Elicited NO Production in Tomato to Influence H2O2 Generation and Increase Host Susceptibility
Contains fulltext :
158667.pdf (publisher's version ) (Open Access)12 p
Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina
Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. To our knowledge, this is the first study of ROS generation associated with NIR-driven oxygenic photosynthesis and it suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance
Reactive oxygen production induced by near-infrared radiation in three strains of the Chl <em>d</em><i>-</i>containing cyanobacterium <i>Acaryochloris marina</i>
Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared-radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance
Reduced nitric oxide levels during drought stress promote drought tolerance in barley and is associated with elevated polyamine biosynthesis
Nitric oxide (NO) is a key messenger in plant stress responses but its exact role in drought response remains unclear. To investigate the role of NO in drought response we employed transgenic barley plants (UHb) overexpressing the barley non-symbiotic hemoglobin gene HvHb1 that oxidizes NO to NO3-. Reduced NO production under drought conditions in UHb plants was associated with increased drought tolerance. Since NO biosynthesis has been related to polyamine metabolism, we investigated whether the observed drought-related NO changes could involve polyamine pathway. UHb plants showed increases in total polyamines and in particular polyamines such as spermidine. These increases correlated with the accumulation of the amino acid precursors of polyamines and with the expression of specific polyamine biosynthesis genes. This suggests a potential interplay between NO and polyamine biosynthesis during drought response. Since ethylene has been linked to NO signaling and it is also related to polyamine metabolism, we explored this connection. In vivo ethylene measurement showed that UHb plants significantly decrease ethylene production and expression of aminocyclopropane-1-carboxylic acid synthase gene, the first committed step in ethylene biosynthesis compared with wild type. These data suggest a NO-ethylene influenced regulatory node in polyamine biosynthesis linked to drought tolerance/susceptibility in barley.publishersversionPeer reviewe
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