Autor: Jackson, M.B. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: A loss of photosynthetic efficiency does not explain stomatal closure in flooded tomato plants
Spadek fotosyntetycznej wydajności nie wyjaśnia zamykania szparek u roślin pomidora w warunkach stresu zalewania
Autorzy:: Janowiak, F.
Else, M.A.
Jackson, M.B.
Tematy:: photosynthetic efficiency
stoma
chlorophyll fluorescence
flooding stress
tomato plant; Pokaż więcej
Wydawca:: Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Powiązania:: https://bibliotekanauki.pl/articles/802005.pdf Link otwiera się w nowym oknie
Opis:: Stomata begin to close within 24 h of imposing soil flooding. We investigated whether the stomatal response was triggered by reduced photosynthetic efficiency in young, fully expanded leaves of flooded plants. Chlorophyll fluorescence measurements indicated that ФpsII the effective quantum yield of PS II,decreased after stomata began to close in flooded plants. Changes in qP mirrored those of ФpsII, ФpsII was not affected by daytime patterns of stomatal conductance in well-drained plants but was reduced by stomatal closure in flooded plants. Fv/Fm a measure of the overall photosynthetic efficiency of dark- adapted plants, decreased after 57 h of flooding. Therefore, prolonged soil flooding adversely affected the thylakoid membranes. QN, a measure of the amount of captured energy dissipated as heat and therefore, unused by the photosynthetic machinery, began to increase after 32 h of flooding and continued to rise thereafter. The interdependence of the changes in chlorophyll fluorescence parameters and the flooding-induced closure of stomata is discussed.
W warunkach nadmiaru wody w glebie szparki u roślin pomidora zamykają się w czasie 24 h. W prezentowanych eksperymentach badano czy ta reakcja szparek była inicjowana przez spadek fotosyntetycznej wydajności młodych, rozwiniętych liści pomidora. Pomiary fluorescencji chlorofilu wykazały, że ФpsII, efektywna wydajność transportu elektronów PSII, spadała dopiero po rozpoczęciu zamykania szparek u zalewanych roślin. Zmiany qP, fotochemicznego wygaszania fluorescencji, odzwierciedlały przebieg ФpsII Na ФpsII nie wpływał okołodobowy rytm szparek u roślin kontrolnych. Natomiast, u roślin zalewanych, ÖpsII spadało wskutek zamykania szparek. Fv/Fm, miara całkowitej wydajności fotosyntetycznej roślin zaadaptowanych do ciemności, spadał po 57 h zalewania roślin. Wskazuje to na niekorzystny wpływ wydłużonego stresu zalewania na membrany tylakoidowe. Niefotochemiczne wygaszanie fluorescencji (NQ), która jest miarą rozpraszania niewykorzystanej energii w postaci ciepła, wzrastała po 32 h od rozpoczęcia stresu zalewania. W pracy dyskutowana jest niezależność zmian parametrów fluorescencji chlorofilu a i indukowanego stresem zalewania zamykania się szparek.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Two-Microphone Dereverberation for Automatic Speech Recognition of Polish
Autorzy:: Kundegorski, M.
Jackson, P. J. B.
Ziółko, B.
Tematy:: speech enhancement
reverberation
automatic speech recognition
ASR
Polish; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/176431.pdf Link otwiera się w nowym oknie
Opis:: Reverberation is a common problem for many speech technologies, such as automatic speech recogni- tion (ASR) systems. This paper investigates the novel combination of precedence, binaural and statistical independence cues for enhancing reverberant speech, prior to ASR, under these adverse acoustical con- ditions when two microphone signals are available. Results of the enhancement are evaluated in terms of relevant signal measures and accuracy for both English and Polish ASR tasks. These show inconsistencies between the signal and recognition measures, although in recognition the proposed method consistently outperforms all other combinations and the spectral-subtraction baseline.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Subarcsecond international LOFAR radio images of the M82 nucleus at 118 MHz and 154 MHz
Autorzy:: Jackson, N.
Wucknitz, O.
Beswick, R.
Haverkorn, M.
Miley, G. K.
Deller, A. T.
Jarvis, M. J.
Moldón, J.
Heald, G.
Toribio, M. C.
White, G. J.
Beck, R.
Carozzi, T. D.
Adebahr, B.
Brüggen, M.
Chyży, Krzysztof
Aalto, S.
Brunetti, G.
Röttgering, H. J. A.
Pérez-Torres, M. A.
Dettmar, R.-J.
Morabito, L. K.
Horellou, C.
Martí-Vidal, I.
Varenius, E.
Conway, J. E.
Best, P.
van Driel, W.
Opis:: Context. The nuclear starburst in the nearby galaxy M82 provides an excellent laboratory for understanding the physics of star formation. This galaxy has been extensively observed in the past, revealing tens of radio-bright compact objects embedded in a diffuse free-free absorbing medium. Our understanding of the structure and physics of this medium in M82 can be greatly improved by high-resolution images at low frequencies where the effects of free-free absorption are most prominent. Aims. The aims of this study are, firstly, to demonstrate imaging using international baselines of the Low Frequency Array (LOFAR), and secondly, to constrain low-frequency spectra of compact and diffuse emission in the central starburst region of M82 via high-resolution radio imaging at low frequencies. Methods. The international LOFAR telescope was used to observe M82 at 110−126 MHz and 146−162 MHz. Images were obtained using standard techniques from very long baseline interferometry. images were obtained at each frequency range: one only using international baselines, and one only using the longest Dutch (remote) baselines. Results. The 154 MHz image obtained using international baselines is a new imaging record in terms of combined image resolution (${0.3}′′$) and sensitivity ($\sigma = 0.15 mJy/beam$) at low frequencies (<327 MHz). We detected 16 objects at 154 MHz, six of these also at 118 MHz. Seven objects detected at 154 MHz have not been catalogued previously. For the nine objects previously detected, we obtained spectral indices and emission measures by fitting models to spectra (combining LOFAR with literature data). Four weaker but resolved features are also found: a linear (50 pc) filament and three other resolved objects, of which two show a clear shell structure. We do not detect any emission from either supernova 2008iz or from the radio transient source 43.78+59.3. The images obtained using remote baselines show diffuse emission, associated with the outflow in M82, with reduced brightness in the region of the edge-on star-forming disk.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: The LOFAR two-metre sky survey : III. First data release : optical/infrared identifications and value-added catalogue
Autorzy:: Kunert-Bajraszewska, M.
Mingo, B.
McKean, J. P.
Shimwell, T. W.
Chyży, Krzysztof
Harwood, J. J.
Hardcastle, M. J.
Urquhart, S.
Iacobelli, M.
Kondapally, R.
Nisbet, D.
Tasse, C.
White, G. J.
Schwarz, D. J.
Prandoni, I.
Hoeft, M.
Jamrozy, Marek
van Weeren, R. J.
Sabater, J.
Gürkan, G.
Mahatma, V. H.
Duncan, K. J.
Cochrane, R. K.
Miley, G. K.
Morabito, L. K.
Best, P. N.
Mechev, A. P.
Williams, W. L.
Shulevski, A.
Roskowinski, C.
Alegre, L.
Jackson, N.
de Gasperin, F.
Röttgering, H. J. A.
Smith, D. J. B.
Croston, J. H.
Hale, C. L.
Callingham, J. R.
Goyal, Arti
Webster, B.
Beswick, R. J.
Opis:: The LOFAR Two-metre Sky Survey (LoTSS) is an ongoing sensitive, high-resolution 120–168 MHz survey of the northern sky with diverse and ambitious science goals. Many of the scientific objectives of LoTSS rely upon, or are enhanced by, the association or separation of the sometimes incorrectly catalogued radio components into distinct radio sources and the identification and characterisation of the optical counterparts to these sources. We present the source associations and optical and/or IR identifications for sources in the first data release, which are made using a combination of statistical techniques and visual association and identification. We document in detail the colour- and magnitude-dependent likelihood ratio method used for statistical identification as well as the Zooniverse project, called LOFAR Galaxy Zoo, used for visual classification. We describe the process used to select which of these two different methods is most appropriate for each LoTSS source. The final LoTSS-DR1-IDs value-added catalogue presented contains 318 520 radio sources, of which 231 716 (73%) have optical and/or IR identifications in Pan-STARRS and WISE.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego