Sumatriptan and Migraine : An Important Advance in Migraine Therapy

Dechant, Kerry L.,Clissold, Stephen P. Medical Publications Korea 1993 Medical Progress Vol.15 No.12

Making full use of hyperspectral data for gross primary productivity estimation with multivariate regression: Mechanistic insights from observations and process-based simulations

Dechant, Benjamin,Ryu, Youngryel,Kang, Minseok American Elsevier Pub. Co 2019 Remote sensing of environment Vol.234 No.-

<P><B>Abstract</B></P> <P>Statistical gross primary productivity (GPP) estimation from remote sensing observations has mostly been attempted on the basis of multispectral observations. To make full use of the information contained in vegetation spectra, however, hyperspectral observations should be used in combination with appropriate multivariate methods. Nevertheless, only very few previous studies attempted to estimate GPP directly from hyperspectral observations and did so on the basis of reflectance, with only a limited number of temporally discontinuous observations. In this study, we used long-term, continuous, half-hourly hyperspectral observations covering the visible and near-infrared spectral range to estimate GPP directly from upwelling irradiance using partial least square (PLS) regression in a rice paddy. To gain a better understanding of processes underlying the PLS estimation, we used extensive complementary field observations to run process-based simulations using the SCOPE model. We then applied PLS regression to the simulated hyperspectral data in the same way as for the observations and disentangled contributions related to relevant physiological processes, namely sun-induced chlorophyll fluorescence (SIF) and xanthophyll cycle-related spectral changes (XC). We found that upwelling hyperspectral irradiance in the visible and near-infrared spectral range predicted GPP better than reflectance. Furthermore, PLS-based GPP estimates outperformed both far-red SIF and widely used vegetation index-based methods. However, the most relevant information for the observation-based PLS-models was not clearly related to XC or SIF as the near-infrared spectral range showed comparable performance. Also, the simple average of upwelling irradiance over the 850–900 nm range outperformed the other non-multivariate approaches, including far-red SIF. These results held for the evaluation in terms of the seasonal variation of GPP, while there was apparently a small contribution of SIF and XC for the diurnal variation. The simulation-based analysis showed that SIF and XC contributed useful information to both GPP and photosynthetic light use efficiency (LUE) estimates at both seasonal and diurnal time scales. The strongest unique contribution from either SIF or XC, however, was to the diurnal variation of GPP and XC showed considerably better performance than SIF. We did not find improvements when combining the spectral regions of XC (500–570 nm) and SIF (650–800 nm) to estimate GPP. While SIF showed improvements when combined with the remaining spectral information excluding XC, this was not the case for XC. Our approach combines the strengths of process-based modeling with multivariate statistical analysis to improve our understanding of the usable information content in vegetation spectra and is highly relevant for further developing suitable methods for GPP estimation at large scales.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hyperspectral GPP estimation outperforms SIF and other multispectral methods. </LI> <LI> Upwelling radiation outperforms reflectance for multivariate GPP estimation. </LI> <LI> Simulated xanthophyll cycle-related spectral changes very promising for GPP. </LI> <LI> No improvements when combining SIF and xanthophyll cycle-related spectral changes. </LI> <LI> Clear discrepancies between main mechanisms for observed and simulated results. </LI> </UL> </P>

Paroxetine

Dechant, Kerry L.,Clissold, Stephen P. Medical Publications Korea 1995 Medical Progress Vol.17 No.1

병원리노베이션 혹은 교체 가격 및 고려사항

토마스 A. 데칸트(Thomas A. Dechant),나용운(나용운 번역) (번역자) 대한설비공학회 2005 대한설비공학회 강연회 및 기타간행물 Vol.- No.-

A practical approach for estimating the escape ratio of near-infrared solar-induced chlorophyll fluorescence

Zeng, Yelu,Badgley, Grayson,Dechant, Benjamin,Ryu, Youngryel,Chen, Min,Berry, J.A. Elsevier 2019 Remote sensing of environment Vol.232 No.-

<P><B>Abstract</B></P> <P>Solar-induced chlorophyll fluorescence (SIF) has emerged as a leading approach for remote sensing of gross primary productivity (GPP). While SIF has an intrinsic, underlying relationship with canopy light capture and light use efficiency, these physiological relationships are obscured by the fact that satellites observe a small and variable fraction of total emitted canopy SIF. Upon emission, most SIF photons are reabsorbed or scattered within the canopy, preventing their observation remotely. The complexities of the radiative transfer process, which vary across time and space, limit our ability to reliably infer physiological processes from SIF observations. Here, we propose an approach for estimating the fraction of total emitted near-infrared SIF (760 nm) photons that escape the canopy by combining the near-infrared reflectance of vegetation (NIR<SUB>V</SUB>) and the fraction of absorbed photosynthetically active radiation (fPAR), two widely available remote sensing products. Our approach relies on the fact that NIR<SUB>V</SUB> is resilient against soil background contamination, allowing us to reliably calculate the bidirectional reflectance factor of vegetation, which in turn conveys information about the escape ratio of SIF photons. Our NIR<SUB>V</SUB>-based approach explains variations in the escape ratio with an <I>R<SUP>2</SUP> </I> of 0.91 and an RMSE of 1.48% across a series of simulations where canopy structure, soil brightness, and sun-sensor-canopy geometry are varied. The approach is applicable to conditions of low leaf area index and fractional vegetation cover. We show that correcting for the escape ratio of SIF using NIR<SUB>V</SUB> provides robust estimates of total emitted SIF, providing for the possibility of studying physiological variations of fluorescence yield at the global scale.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The escape ratio of near-infrared SIF can be estimated using NIR<SUB>V</SUB> and fPAR. </LI> <LI> The approach applies broadly, including sparse canopies with bright soil backgrounds. </LI> <LI> The approach allows estimation of total emitted SIF from directional SIF data. </LI> </UL> </P>

Exploring the spatial relationship between airborne-derived red and far-red sun-induced fluorescence and process-based GPP estimates in a forest ecosystem

Tagliabue, Giulia,Panigada, Cinzia,Dechant, Benjamin,Baret, Fré,dé,ric,Cogliati, Sergio,Colombo, Roberto,Migliavacca, Mirco,Rademske, Patrick,Schickling, Anke,Schü,ttemeyer, Dirk,Verre Elsevier 2019 Remote sensing of environment Vol.231 No.-

<P><B>Abstract</B></P> <P>Terrestrial gross primary productivity (GPP) plays an essential role in the global carbon cycle, but the quantification of the spatial and temporal variations in photosynthesis is still largely uncertain. Our work aimed to investigate the potential of remote sensing to provide new insights into plant photosynthesis at a fine spatial resolution. This goal was achieved by exploiting high-resolution images acquired with the FLuorescence EXplorer (FLEX) airborne demonstrator <I>HyPlant</I>. The sensor was flown over a mixed forest, and the images collected were elaborated to obtain two independent indicators of plant photosynthesis. First, maps of sun-induced chlorophyll fluorescence (F), a novel indicator of plant photosynthetic activity, were successfully obtained at both the red and far-red peaks (r<SUP>2</SUP> = 0.89 and <I>p</I> < 0.01, r<SUP>2</SUP> = 0.77 and p < 0.01, respectively, compared to top-of-canopy ground-based measurements acquired synchronously with the overflight) over the forested study area. Second, maps of GPP and absorbed photosynthetically active radiation (APAR) were derived using a customised version of the coupled biophysical model Breathing Earth System Simulator (BESS). The model was driven with airborne-derived maps of key forest traits (i.e., leaf chlorophyll content (LCC) and leaf area index (LAI)) and meteorological data providing a high-resolution snapshot of the variables of interest across the study site. The LCC and LAI were accurately estimated (RMSE = 5.66 μg cm<SUP>−2</SUP> and RMSE = 0.51 m<SUP>2</SUP> m<SUP>−2</SUP>, respectively) through an optimised Look-Up-Table-based inversion of the PROSPECT-4-INFORM radiative transfer model, ensuring the accurate representation of the spatial variation of these determinants of the ecosystem's functionality. The spatial relationships between the measured F and modelled BESS outputs were then analysed to interpret the variability of ecosystem functioning at a regional scale. The results showed that far-red F is significantly correlated with the GPP (r<SUP>2</SUP> = 0.46, <I>p</I> < 0.001) and APAR (r<SUP>2</SUP> = 0.43, p < 0.001) in the spatial domain and that this relationship is nonlinear. Conversely, no statistically significant relationships were found between the red F and the GPP or APAR (<I>p</I> > 0.05). The spatial relationships found at high resolution provide valuable insight into the critical role of spatial heterogeneity in controlling the relationship between the far-red F and the GPP, indicating the need to consider this heterogeneity at a coarser resolution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High-resolution LCC and LAI maps were obtained from <I>HyPlant</I> through RTM inversion. </LI> <LI> High-resolution GPP and APAR maps were obtained driving BESS with <I>HyPlant</I> data. </LI> <LI> High-resolution F<SUB>687</SUB> and F<SUB>760</SUB> maps were obtained from <I>HyPlant</I> using SFM in a forest. </LI> <LI> F<SUB>687</SUB> showed a non-significant relation with GPP and APAR in the spatial domain. </LI> <LI> F<SUB>760</SUB> showed a positive nonlinear relation with GPP and APAR in the spatial domain. </LI> </UL> </P>

Sun-induced chlorophyll fluorescence is more strongly related to absorbed light than to photosynthesis at half-hourly resolution in a rice paddy

Yang, Kaige,Ryu, Youngryel,Dechant, Benjamin,Berry, Joseph A.,Hwang, Yorum,Jiang, Chongya,Kang, Minseok,Kim, Jongmin,Kimm, Hyungsuk,Kornfeld, Ari,Yang, Xi Elsevier 2018 Remote sensing of environment Vol.216 No.-

<P><B>Abstract</B></P> <P>Sun-induced chlorophyll fluorescence (SiF) is increasingly used as a proxy for vegetation canopy photosynthesis. While ground-based, airborne, and satellite observations have demonstrated a strong linear relationship between SiF and gross primary production (GPP) at seasonal scales, their relationships at high temporal resolution across diurnal to seasonal scales remain unclear. In this study, far-red canopy SiF, GPP, and absorbed photosynthetically active radiation (APAR) were continuously monitored using automated spectral systems and an eddy flux tower over an entire growing season in a rice paddy. At half-hourly resolution, strong linear relationships between SiF and GPP (R<SUP>2</SUP> = 0.76) and APAR and GPP (R<SUP>2</SUP> = 0.76) for the whole growing season were observed. We found that relative humidity, diffuse PAR fraction, and growth stage influenced the relationships between SiF and GPP, and APAR and GPP, and incorporating those factors into multiple regression analysis led to improvements up to R<SUP>2</SUP> = 0.83 and R<SUP>2</SUP> = 0.88, respectively. Relationships between LUE<SUB>p</SUB> (=GPP/APAR) and LUE<SUB>f</SUB> (=SiF/APAR) were inconsistent at half-hourly and weak at daily resolutions (R<SUP>2</SUP> = 0.24). Both at diurnal and seasonal time scales with half-hourly resolution, we found considerably stronger linear relationships between SiF and APAR than between either SiF and GPP or APAR and GPP. Overall, our results indicate that for subdiurnal temporal resolution, canopy SiF in the rice paddy is above all a very good proxy for APAR at diurnal and seasonal time scales and that therefore SiF-based GPP estimation needs to take into account relevant environmental information to model LUE<SUB>p</SUB>. These findings can help develop mechanistic links between canopy SiF and GPP across multiple temporal scales.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Observed SiF is a better proxy of APAR than GPP. </LI> <LI> Found considerable environmental effects on the SiF-GPP relationships </LI> <LI> Improved GPP estimation by combining SiF or APAR with environmental variables </LI> <LI> Contribute to canopy SiF-GPP mechanistic links across multiple temporal scales </LI> </UL> </P>

Protein kinase C and calcineurin cooperatively mediate cell survival under compressive mechanical stress

Mishra, Ranjan,van Drogen, Frank,Dechant, Reinhard,Oh, Soojung,Jeon, Noo Li,Lee, Sung Sik,Peter, Matthias National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.51

<P><B>Significance</B></P><P>Cells are constantly exposed to a variety of mechanical cues, and respond by activating conserved signaling pathways that modulate their profiliation and intracellular organization. For instance, cells in solid tumors experience sustained compression from the microenvironment, and compressive stress is known to trigger an invasive phenotype in some cancer cells. However, despite its importance for health and disease, the specific mechanosensors and the downstream signaling network mediating these physiological responses remain largely unknown, in part due to the lack of appropriate experimental systems. Here, we develop a microfluidic platform that allows triggering compressive mechanical stress in a reversible and controllable manner, and we identify cell surface receptors that specifically sense compressive mechanical stress and generate synergistic cellular responses.</P><P>Cells experience compressive stress while growing in limited space or migrating through narrow constrictions. To survive such stress, cells reprogram their intracellular organization to acquire appropriate mechanical properties. However, the mechanosensors and downstream signaling networks mediating these changes remain largely unknown. Here, we have established a microfluidic platform to specifically trigger compressive stress, and to quantitatively monitor single-cell responses of budding yeast in situ. We found that yeast senses compressive stress via the cell surface protein Mid2 and the calcium channel proteins Mid1 and Cch1, which then activate the Pkc1/Mpk1 MAP kinase pathway and calcium signaling, respectively. Genetic analysis revealed that these pathways work in parallel to mediate cell survival. Mid2 contains a short intracellular tail and a serine−threonine-rich extracellular domain with spring-like properties, and both domains are required for mechanosignaling. Mid2-dependent spatial activation of the Pkc1/Mpk1 pathway depolarizes the actin cytoskeleton in budding or shmooing cells, thereby antagonizing polarized growth to protect cells under compressive stress conditions. Together, these results identify a conserved signaling network responding to compressive mechanical stress, which, in higher eukaryotes, may ensure cell survival in confined environments.</P>