Search results for "Optical"
showing 10 items of 7671 documents
Theoretical characterization of the electronic properties of unsymmetrical phthalocyanine analogues
1993
Abstract The electronic structure of unsymmetrical phthalocyanine-based compounds is investigated using the nonempirical valence effective Hamiltonian (VEH) method. The VEH results predict a slight but continuous destabilization of the HOMO level and a monotonous narrowing of the HOMO-LUMO energy gap as the size of the system increases. The theoretical trends are found to agree with optical absorption experimental data and show that the optical properties of phthalocyanine can be monitored by adjusting the size of the π-conjugated macrocycle.
From corona virus to corona crisis : the value of an analytical and geographical understanding of crisis
2020
Abstract The term ‘crisis’ is omnipresent. The current corona virus pandemic is perceived as the most recent example. However, the notion of crisis is increasingly deployed as a signifier of relevance, rather than as an analytical concept. Moreover, human geography has so far little contributed to the interdisciplinary crisis research field which is fixated on the temporal aspects of crisis but neglects its spatiality. Against this background, the first aim of the paper is to demonstrate the value of thinking about crisis analytically. Therefore, we introduce theoretical knowledge developed within a recently emerging literature on crisis management. Second, we demonstrate the relevance of i…
Water Adsorption in Flexible Gallium-Based MIL-53 Metal–Organic Framework
2014
Understanding the adsorption of water in metal–organic frameworks (MOF), and particularly in soft porous crystals, is a crucial prerequisite before considering MOFs for industrial applications. We report here a joint experimental and theoretical study on the behavior of a gallium-based breathing MOF, Ga-MIL-53, upon water adsorption. By looking at the energetics and thermodynamics of Ga-MIL-53, we demonstrate why it behaves differently from its sibling Al-MIL-53, showing a different phase at room temperature (a nonporous phase) and the presence of a hydrated narrow-pore structure at gas saturation pressure. Moreover, we present a complete water vapor pressure vs temperature phase diagram of…
Treat and extend versus fixed regimen in neovascular age related macular degeneration: A systematic review and meta-analysis
2020
Purpose: To compare efficacy of treat and extend (T&E) versus fixed regimen treatment protocols in neovascular age-related macular degeneration (nAMD). Methods: Randomized clinical trials (RCTs) comparing T&E versus fixed regimen protocols for nAMD were systematically searched. Primary outcome was to compare the mean best corrected visual acuity (BCVA) change in T&E regimen versus fixed regimen. Secondary outcomes were change in the mean optical coherence tomography (OCT) central retinal thickness (CRT) and mean number of injections. Standardized mean difference (SMD) along with 95% confidence intervals (CIs) were calculated. Random-effect models were used for meta-analyses. Res…
Early OCTA Changes of Type 3 Macular Neovascularization Following Brolucizumab Intravitreal Injections
2022
Background and Objectives: Brolucizumab is a novel anti-vascular endothelial growth factor (VEGF), whose efficacy has been shown in the Hawk and Harrier phase 3 clinical studies. The goal of the present case series is to report initial results of brolucizumab intravitreal injections (IVI) on type 3 neovascularization in neovascular age-related macular degeneration (nAMD), evaluated by optical coherence tomography angiography (OCTA). Materials and Methods: This is a bicentric retrospective case series. Patients with newly diagnosed type 3 MNV treated with brolucizumab IVI and at least 6 months follow-up were enrolled. OCTA en face images and B-scans were analyzed for lesions at baseline, 1 m…
First Retrievals of ASCAT-IB VOD (Vegetation Optical Depth) at Global Scale
2021
Global and long-term vegetation optical depth (VOD) dataset are very useful to monitor the dynamics of the vegetation features, climate and environmental changes. In this study, the radar-based global ASCAT (Advanced SCATterometer) IB (INRAE-BORDEAUX) VOD was retrieved using a model which was recently calibrated over Africa. In order to assess the performance of IB VOD, the Saatchi biomass and three other VOD datasets (ASCAT V16, AMSR2 LPRM V5 and VODCA LPRM V6) derived from C-band observations were used in the comparison. The preliminary results show that IB VOD has a promising ability to predict biomass $(\mathrm{R}=0.74,\ \text{RMSE} =44.82\ \text{Mg}\ \text{ha}^{-1})$ , which is better …
A combined optical-microwave method to retrieve soil moisture over vegetated areas
2011
A simple approach for correcting for the effect of vegetation in the estimation of the surface soil moisture (wS) from L-band passive microwave observations is presented in this study. The approach is based on semi-empirical relationships between soil moisture and the polarized reflectivity including the effect of the vegetation optical depth which is parameterized as a function of the normalized vegetation difference index (NDVI). The method was tested against in situ measurements collected over a grass site from 2004 to 2007 (SMOSREX experiment). Two polarizations (horizontal/vertical) and five incidence angles (20◦, 30◦, 40◦, 50◦, and 60◦) were considered in the analysis. The best wS est…
Global Long-Term Brightness Temperature Record from L-Band SMOS and Smap Observations
2021
Passive microwave remote sensing observations at L-band provide key and global information on surface soil moisture (SM) and vegetation optical depth (VOD), which are related to the Earth water and carbon cycles. Only two spaceborne L-band sensors are currently operating: SMOS, launched end of 2009 and thus providing now a 11-year global dataset and SMAP, launched beginning of 2015. To ensure SM and L-VOD data continuity in the event of failure of one of the space-borne SMOS or SMAP sensors, we developed a consistent brightness temperature (TB) record by first producing consistent 40° SMOS and SMAP TB estimates based on SMOS-IC and SMAP enhanced data resp., and then fusing them via linear f…
Intra-visual conflict in visually induced motion sickness
2011
Abstract Motion sickness (MS) can be a debilitating side-effect not just of sea travel, but also when immersed in video games or virtual environments (visually induced MS). To explore the impact of visual display parameters on motion sickness, we presented footage taken on an automobile race track to different groups of observers during three experiments. In Experiment 1, one group watched the movie wearing a head-mounted display (HMD) and a second group looked at a large projection screen with unrestricted view. Resolution and visual angle were equated. In contrast to common assumption, the projection screen produced significantly higher motion sickness scores than the HMD. To understand t…
Biophotonics in veterinary medicine: the first steps toward clinical translation
2019
In this paper, we analyzed the current situation and the potential of biophotonics and biomedical optics in veterinary medicine. Promising optical techniques such as optical coherence tomography, pulse oximeter, and hyperspectral imaging have been clinically translated into human medicine. But even though human and small animal medicine share personalized and state-of-the-art approach, biophotonics remains rarely exploited in the canine and feline medicine. However, there are some biophotonics studies in veterinary oncology which addressed tumor diagnosis (skin and subcutaneous tumors), prognosis (lymphoma), and therapy (clear surgical margins). Visible and near-infrared spectroscopy served…