Search results for "photo"
showing 10 items of 11789 documents
Determinants of the interannual relationships between remote sensed photosynthetic activity and rainfall in tropical Africa
2007
International audience; The response of photosynthetic activity to interannual rainfall variations in Africa South of the Sahara is examined using 20 years (1981-2000) of Normalised Difference Vegetation Index (NDVI) AVHRR data. Linear correlations and regressions were computed between annual NDVI and annual rainfall at a 0.5° latitude/longitude resolution, based on two gridded precipitation datasets (Climate Prediction Center Merged Analysis of Precipitation [CMAP] and Climatic Research Unit [CRU]). The spatial patterns were then examined to detect how they relate to the mean annual rainfall amounts, land-cover types as from the Global Land Cover 2000 data set, soil properties and soil typ…
Strongly Coupled Coherent Phonons in Single-Layer MoS 2
2019
We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution ($\sim$20fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We generate and detect coherent phonons (CPs) in single layer (1L) MoS$_2$, as a representative semiconducting 1L-transition metal dichalcogenide (TMD), where the confined dynamical interaction between excitons and phonons is unexplored. The coherent oscillatory motion of the out-of-plane $A'_{1}$ phonons, triggered by the ultrashort laser pulses, dynamically modulates the excitonic resonances on a timescale of few tens fs. We observe an enhancement by…
Global Estimation of Biophysical Variables from Google Earth Engine Platform
2018
This paper proposes a processing chain for the derivation of global Leaf Area Index (LAI), Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), Fraction Vegetation Cover (FVC), and Canopy water content (CWC) maps from 15-years of MODIS data exploiting the capabilities of the Google Earth Engine (GEE) cloud platform. The retrieval chain is based on a hybrid method inverting the PROSAIL radiative transfer model (RTM) with Random forests (RF) regression. A major feature of this work is the implementation of a retrieval chain exploiting the GEE capabilities using global and climate data records (CDR) of both MODIS surface reflectance and LAI/FAPAR datasets allowing the global estim…
KOSMOS 2017 Peru Side Experiment: nutrients, phytoplankton abundances, enzyme rates, photophysiology
2022
This data was collected during an short-term incubation experiment in March 2017 that investigated the response of a surface plankton community to upwelling. This experiment was carried in the framework of the SFB754-funded KOSMOS mesocosm study that took place in La Punta, Callao, Peru between February-April 2017. A total of six different treatments were used to disentangle chemical and biological characteristics of deep water that influence surface plankton blooms: 2 different deep water sources with different nutrient concentrations; 3 treatments to distinguish the effects of inorganic nutrients, organic nutrients and deep water microbial populations. Measured variables include inorganic…
Photocycle of point defects in highly- and weakly-germanium doped silica revealed by transient absorption measurements with femtosecond tunable pump.
2022
AbstractWe report pump-probe transient absorption measurements addressing the photocycle of the Germanium lone pair center (GLPC) point defect with an unprecedented time resolution. The GLPC is a model point defect with a simple and well-understood electronic structure, highly relevant for several applications. Therefore, a full explanation of its photocycle is fundamental to understand the relaxation mechanisms of such molecular-like systems in solid state. The experiment, carried out exciting the sample resonantly with the ultraviolet (UV) GLPC absorption band peaked at 5.1 eV, gave us the possibility to follow the defect excitation-relaxation dynamics from the femto-picosecond to the nan…
Initial results of the Italian project on direct georeferencing in aerial Photogrammetry
2004
The paper describes one of the first outcomes of an Italian national research Project on inertial positioning in photogrammetry. The focus of the paper is on the quality which is attainable from direct photogrammetry in an industrial production context. Even if GPS/IMU-aided photogrammetry is used rather widely, it is still useful to perform rigorous quality assessment of this method, because large and diverse case studies are necessary to prove and quantify the capability of a new methodology. Besides, it is necessary to evaluate such methodology in the ordinary operational conditions, rather than considering data acquired in a dedicated, special context. To fulfil these requirements sever…
Gingivīta novērtēšana, izmantojot attālinātu fotopletismogrāfiju
2020
Pētījuma mērķis ir novērtēt smaganu perfūziju izmeklējamām personām izmantojot photopletizmogrāfijas metodi. Viens no pētījuma mērķiem bija reģistrēt kapsacīna izraisīto neiro-iekaisuma efektu. Metodoloģija Šķērsgriezuma pētījums, tika veikts iekļaujot nelielu izmeklējamo personu grupu , izmeklējamās personas pirms pētījuma veikšanas tika iepazīstinātas ar protokolu un rakstiski apstiprināja dalību pētījumā. Pētījuma gaitā smaganu perfūzijas tika reģistrēta miera apstākļos, un aplicējot uz smaganu virsmas kapsacīnu saturošu piparu ekstraktu, kas izraisīja pārejošu neirogēnu iekaisumu, ar tam raksturīgo hiperēmiju. Signāla reģistrācija tika veikta novietojot uz galvas izmeklējamai personai f…
Additional testimony. Photographs in the prose of Daša Drndić
2020
In this paper I will reflect on the role of photographs in the works of Daša Drndić. Mixing fictional and documentary modes is a characteristic feature of her texts. It is achieved among others by utilizing visual representations of the past. In my paper I aim to outline the strategies of visualization applied by the authoress (especially the traumatic, Holocaust-related experience), which materialize through photographs included in her works of literature. In the case of Drndić the visuals include for instance contemporary or archival photographs of places marked by the Holocaust and of Jewish inhabitants of Vienna as well as portraits of war criminals. Generally speaking, in her texts the…
Synthesis, Electrochemistry, and Photophysics of Aza-BODIPY Porphyrin Dyes
2016
International audience; The synthesis of dyad and triad aza-BODIPY-porphyrin systems in two steps starting from an aryl-substituted aza-BODIPY chromophore is described. The properties of the resulting aza-BODIPY-porphyrin conjugates have been extensively investigated by means of electrochemistry, spectroelectrochemistry, and absorption/emission spectroscopy. Fluorescence measurements have revealed a dramatic loss of luminescence intensity, mainly due to competitive energy transfer and photoinduced electron transfer involving charge separation followed by recombination.
Photoinduced lethal and sublethal toxicity of retene, a polycyclic aromatic hydrocarbon derived from resin acid, to coregonid larvae
2004
A comparative investigation on the acute phototoxicity of retene to vendace (Coregonus albula) and whitefish (C. lavaretus), both having pelagial larvae in spring, was conducted. To test the concept of early warning of sublethal biomarkers in relation to lethality to posthatch stages, we examined the effects of ultraviolet-B (UV-B) and retene on the levels of cytochrome P4501A (CYP1A) and heat shock protein 70 (HSP70) by exposing the animals to elevated levels of these factors for 48 and 72 h, respectively. Whereas UV-B and retene on their own were not lethal, simultaneous retene and UV-B exposure caused very high mortality to both species. The median lethal concentration (LC50; i.e., the c…