Effects of grazing exclusion and shrub encroachment on the ecosystem ecology of evergreen oak woodland

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaShrub encroachment, an increase in density and cover of shrub plant communities, is affecting biodiversity and functioning of ecosystems around the world. Through feeding and trampling ungulates affect the structure and species composition of plant communities, including shrublands, and are key drivers in shrub encroachment processes. This thesis, conducted within a long-term browsing exclosure experiment, investigates the effects of ungulates (red deer Cervus elaphus and fallow deer Dama dama) on the encroachment of C. ladanifer, a dominant Mediterranean shrub, into a mixed cork (Quercus suber) and holm (Quercus rotundifolia) evergreen oak woodland in Southern Portugal. Five paired fenced (ungulate-excluded) and unfenced (ungulate-allowed) plots of 25 m x 25 m were established in the study area in July 2001. Fenced plots had a 2.20 m height fence to exclude deer occurring in the site. Data on C. ladanifer reproduction structures (buds, fruits and flowers), soil seed bank, population density and biomass, were collected in fenced and open plots in 2007, 2013 and 2015. Ungulates consumed buds, flowers and fruits and decreased the soil seed bank of C. ladanifer. Plant reproductive costs (loss of fruits) were higher than potential benefits (seed dissemination) and the population density and biomass of C. ladanifer, decreased in the open plots by the end of the experiment. Ungulates decreased above-ground carbon (C) storage but also the amount of fine fuel loads reducing fire hazard and the probability of crown fires, and consequent adult oak mortality, in open plots. Therefore ungulate may potential benefit long-term ecosystem C storage. A drought year during data monitoring allowed quantifying jointly effects of ungulate browsing and drought on C. ladanifer mortality which increased in open plots. Changes in live:dead plant biomass affected fire hazard. Results show that ungulate ecology needs to be considered when investigating shrub encroachment processesN/

CNN-based real-time 2D-3D deformable registration from a single X-ray projection

Purpose: The purpose of this paper is to present a method for real-time 2D-3D non-rigid registration using a single fluoroscopic image. Such a method can find applications in surgery, interventional radiology and radiotherapy. By estimating a three-dimensional displacement field from a 2D X-ray image, anatomical structures segmented in the preoperative scan can be projected onto the 2D image, thus providing a mixed reality view. Methods: A dataset composed of displacement fields and 2D projections of the anatomy is generated from the preoperative scan. From this dataset, a neural network is trained to recover the unknown 3D displacement field from a single projection image. Results: Our method is validated on lung 4D CT data at different stages of the lung deformation. The training is performed on a 3D CT using random (non domain-specific) diffeomorphic deformations, to which perturbations mimicking the pose uncertainty are added. The model achieves a mean TRE over a series of landmarks ranging from 2.3 to 5.5 mm depending on the amplitude of deformation. Conclusion: In this paper, a CNN-based method for real-time 2D-3D non-rigid registration is presented. This method is able to cope with pose estimation uncertainties, making it applicable to actual clinical scenarios, such as lung surgery, where the C-arm pose is planned before the intervention

Measurements of atmospheric and oceanic CO2 in the tropical Atlantic : 10 years after the 1982-1984 FOCAL cruises

Measurements of CO2 parameters in and over the tropical Atlantic ocean have been made during the CITHER 1 cruise (January to March 1993). These observations are compared to the results obtained a decade earlier in the same area during the FOCAL experiment (1982-1984). The increase of atmospheric CO2 (1.3 to 1.5 ppm yr-1) is in agreement with the secular trend. The variation of CO2 fugacity, fCO2, in surface seawater is analysed and compared with variations of hydrographic conditions. The apparent increase of ocean surface fCO2 is somewhat higher than the atmospheric increase: during the 9-year period, the apparent increase of oceanic fCO2 is found to range from 22.5 to 24.9 µatm. A new estimate of air-sea CO2 flux in the Atlantic equatorial belt indicates that the oceanic source is enhanced in 1993 compared to 1984. An interannual change in total inorganic carbon, TCO2, through the accumulation of CO2 in the mixed layer is assessed and analysed in comparison with the fCO2 increase. The agreement between the evolutions of the two parameters of the oceanic CO2 system is acceptable by taking into account the uncertainties to estimate these evolutions. (Résumé d'auteur

Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb

The quest for extrasolar planets and their characterisation as well as studies of fundamental physics on cosmological scales rely on capabilities of high-resolution astronomical spectroscopy. A central requirement is a precise wavelength calibration of astronomical spectrographs allowing for extraction of subtle wavelength shifts from the spectra of stars and quasars. Here, we present an all-fibre, 400 nm wide near-infrared frequency comb based on electro-optic modulation with 14.5 GHz comb line spacing. Tests on the high-resolution, near-infrared spectrometer GIANO-B show a photon-noise limited calibration precision of <10 cm/s as required for Earth-like planet detection. Moreover, the presented comb provides detailed insight into particularities of the spectrograph such as detector inhomogeneities and differential spectrograph drifts. The system is validated in on-sky observations of a radial velocity standard star (HD221354) and telluric atmospheric absorption features. The advantages of the system include simplicity, robustness and turn-key operation, features that are valuable at the observation sites

Nouveaux agents anti-inflammatoires en série N-(4-pyridyl)alcanesulfonamide

peer reviewedaudience: researcher, professional, studen