Determination of Evapotranspiration and Crop Coefficient of Cactus Pear (Opuntia ficus-indica Mill.) with an Energy Balance Technique

A micrometeorological approach based on surface renewal technique was adopted to estimate evapotranspiration fluxes and crop coefficient data from an irrigated cactus pear (Opuntia ficus-indica Mill.) orchard under Mediterranean climatic conditions. High-frequency temperature readings were taken above the canopy top in order to get surface renewal sensible heat flux values (HSR). These values were compared against eddy covariance sensible heat fluxes (HEC) for calibration. Latent heat flux (or evapotranspiration, ET) was obtained as the residual of the energy balance equation using HSR. In field measurements of biophysical crop features, physiological characteristic and soil hydraulic components were integrated with the analysis of the surface energy fluxes. Microlysimeters were used to compute evaporation rates, allowing the separation of transpiration from ET data. During the irrigation season, evapotranspiration from the cactus pear orchard was 330 mm of water producing 16,210 kg of dry matter ha-1 for a biomass water productivity: WPb = kg biomass m-2 per kg H2O m-2 = 6.6 710-3. The water use efficiency (WUE) was 204 kg H2O kg-1 dry matter. The low value of WPb, relative to other CAM plants, suggests an opportunity to improve the use of irrigation water

Determination of Evapotranspiration and Annual Biomass Productivity of a Cactus Pear [Opuntia ficus-indica L. (Mill.)] Orchard in a Semiarid Environment

A micrometeorological approach based on the surface energy balance was adopted to estimate evapotranspiration fluxes and crop coefficient data from an irrigated cactus pear [Opuntia ficus-indica L. (Mill.)] orchard under Mediterranean climatic conditions. Highfrequency temperature readings were taken above the canopy top to get sensible heat flux values (HSR) using the surface renewal technique. These values were compared against eddy covariance sensible heat fluxes (HEC) for calibration. Latent heat flux (or evapotranspiration, ET) was obtained by solving the daily energy balance equation. Measurements of soil hydraulic components were integrated with the analysis of the surface energy fluxes and crop development in terms of phenology and aboveground biomass accumulation. Microlysimeters were used to compute evaporation rates, allowing the separation of daily transpiration from ET data. Ecophysiological measurements were carried to estimate dry weight accumulation and partitioning. Cactus pear evapotranspired a total of approximately 286 and 252 mm of water during the two monitored growing seasons, respectively. Average daily values of crop (ETc) and reference (ET0) evapotranspiration were in the order of 2.5 and 5.0 mm, respectively, with a corresponding value of the mean crop coefficient of approximately 0.40. The annual dry mass fixed per single tree was 38.8 1.3 kg, with a total production of 12.9 t ha 121, which is comparable to many C3 and C4 plants and resulted in a water use efficiency (WUE) of 4.6 and 4.4 gDMkgH2O 121 in 2009 and 2010, respectively. The stem area index (SAI) was 3.5

A Case Report of a Mediastinal Fistula with Liver Abscesses as a Complication of Aortic Valve Replacement Surgery

We report a case of mediastinal fistula with liver abscesses detected by thoracic and abdominal computed tomography as a complication of aortic valve replacement surgery

An accessibility planning tool for network transit oriented development: SNAP

In the academic debate regarding the influences between urban form, built environment and travel patterns, a specific idea that has taken hold is that more compact urban development around railway stations, often referred to as Transit Oriented Development (TOD), contributes to the control of vehicle travel and to more sustainable metropolitan systems. According to this general principle this work proposes a GIS accessibility tool for the design of polycentric transit oriented scenario: SNAP - Station Network Accessibility Planning tool. In the first part the state of the art on Transit Oriented Development policies in Europe is presented with a focus on three study cases. In the second part the SNAP tool is described, with remarks to the approach, the methodology and the used indicators. Furthermore the paper discusses an application to the metropolitan area of Naples

Advanced perfusion quantification methods for dynamic PET and MRI data modelling

The functionality of tissues is guaranteed by the capillaries, which supply the microvascular network providing a considerable surface area for exchanges between blood and tissues. Microcirculation is affected by any pathological condition and any change in the blood supply can be used as a biomarker for the diagnosis of lesions and the optimization of the treatment. Nowadays, a number of techniques for the study of perfusion in vivo and in vitro are available. Among the several imaging modalities developed for the study of microcirculation, the analysis of the tissue kinetics of intravenously injected contrast agents or tracers is the most widely used technique. Tissue kinetics can be studied using different modalities: the positive enhancement of the signal in the computed tomography and in the ultrasound dynamic contrast enhancement imaging; T1-weighted MRI or the negative enhancement of T2* weighted MRI signal for the dynamic susceptibility contrast imaging or, finally, the uptake of radiolabelled tracers in dynamic PET imaging. Here we will focus on the perfusion quantification of dynamic PET and MRI data. The kinetics of the contrast agent (or the tracer) can be analysed visually, to define qualitative criteria but, traditionally, quantitative physiological parameters are extracted with the implementation of mathematical models. Serial measurements of the concentration of the tracer (or of the contrast agent) in the tissue of interest, together with the knowledge of an arterial input function, are necessary for the calculation of blood flow or perfusion rates from the wash-in and/or wash-out kinetic rate constants. The results depend on the acquisition conditions (type of imaging device, imaging mode, frequency and total duration of the acquisition), the type of contrast agent or tracer used, the data pre-processing (motion correction, attenuation correction, correction of the signal into concentration) and the data analysis method. As for the MRI, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a non-invasive imaging technique that can be used to measure properties of tissue microvasculature. It is sensitive to differences in blood volume and vascular permeability that can be associated with tumour angiogenesis. DCE-MRI has been investigated for a range of clinical oncologic applications (breast, prostate, cervix, liver, lung, and rectum) including cancer detection, diagnosis, staging, and assessment of treatment response. Tumour microvascular measurements by DCE-MRI have been found to correlate with prognostic factors (such as tumour grade, microvessel density, and vascular endothelial growth factor expression) and with recurrence and survival outcomes. Furthermore, DCE-MRI changes measured during treatment have been shown to correlate with outcome, suggesting a role as a predictive marker. The accuracy of DCE-MRI relies on the ability to model the pharmacokinetics of an injected contrast agent using the signal intensity changes on sequential magnetic resonance images. DCE-MRI data are usually quantified with the application of the pharmacokinetic two-compartment Tofts model (also known as the standard model), which represents the system with the plasma and tissue (extravascular extracellular space) compartments and with the contrast reagent exchange rates between them. This model assumes a negligible contribution from the vascular space and considers the system in, what-is-known as, the fast exchange limit, assuming infinitely fast transcytolemmal water exchange kinetics. In general, the number, as well as any assumption about the compartments, depends on the properties of the contrast agent used (mainly gadolinium) together with the tissue physiology or pathology studied. For this reason, the choice of the model is crucial in the analysis of DCE-MRI data. The value of PET in clinical oncology has been demonstrated with studies in a variety of cancers including colorectal carcinomas, lung tumours, head and neck tumours, primary and metastatic brain tumours, breast carcinoma, lymphoma, melanoma, bone cancers, and other soft-tissue cancers. PET studies of tumours can be performed for several reasons including the quantification of tumour perfusion, the evaluation of tumour metabolism, the tracing of radiolabelled cytostatic agents. In particular, the kinetic analysis of PET imaging has showed, in the past few years, an increasing value in tumour diagnosis, as well as in tumour therapy, through providing additional indicative parameters. Many authors have showed the benefit of kinetic analysis of anticancer drugs after labelling with radionuclide in measuring the specific therapeutic effect bringing to light the feasibility of applying the kinetic analysis to the dynamic acquisition. Quantification methods can involve visual analysis together with compartmental modelling and can be applied to a wide range of different tracers. The increased glycolysis in the most malignancies makes 18F-FDG-PET the most common diagnostic method used in tumour imaging. But, PET metabolic alteration in the target tissue can depend by many other factors. For example, most types of cancer are characterized by increased choline transport and by the overexpression of choline kinase in highly proliferating cells in response to enhanced demand of phosphatidylcholine (prostate, breast, lung, ovarian and colon cancers). This effect can be diagnosed with choline-based tracers as the 18Ffluoromethylcholine (18F-FCH), or the even more stable 18F-D4-Choline. Cellular proliferation is also imaged with 18F-fluorothymidine (FLT), which is trapped within the cytosol after being mono phosphorylated by thymidine kinase-1 (TK1), a principal enzyme in the salvage pathway of DNA synthesis. 18F-FLT has been found to be useful for noninvasive assessment of the proliferation rate of several types of cancer and showed high reproducibility and accuracy in breast and lung cancer tumours. The aim of this thesis is the perfusion quantification of dynamic PET and MRI data of patients with lung, brain, liver, prostate and breast lesions with the application of advanced models. This study covers a wide range of imaging methods and applications, presenting a novel combination of MRI-based perfusion measures with PET kinetic modelling parameters in oncology. It assesses the applicability and stability of perfusion quantification methods, which are not currently used in the routine clinical practice. The main achievements of this work include: 1) the assessment of the stability of perfusion quantification of D4-Choline and 18F-FLT dynamic PET data in lung and liver lesions, respectively (first applications in the literature); 2) the development of a model selection in the analysis of DCE-MRI data of primary brain tumours (first application of the extended shutter speed model); 3) the multiparametric analysis of PET and MRI derived perfusion measurements of primary brain tumour and breast cancer together with the integration of immuohistochemical markers in the prediction of breast cancer subtype (analysis of data acquired on the hybrid PET/MRI scanner). The thesis is structured as follows: - Chapter 1 is an introductive chapter on cancer biology. Basic concepts, including the causes of cancer, cancer hallmarks, available cancer treatments, are described in this first chapter. Furthermore, there are basic concepts of brain, breast, prostate and lung cancers (which are the lesions that have been analysed in this work). - Chapter 2 is about Positron Emission Tomography. After a brief introduction on the basics of PET imaging, together with data acquisition and reconstruction methods, the chapter focuses on PET in the clinical settings. In particular, it shows the quantification techniques of static and dynamic PET data and my results of the application of graphical methods, spectral analysis and compartmental models on dynamic 18F-FDG, 18F-FLT and 18F-D4- Choline PET data of patients with breast, lung cancer and hepatocellular carcinoma. - Chapter 3 is about Magnetic Resonance Imaging. After a brief introduction on the basics of MRI, the chapter focuses on the quantification of perfusion weighted MRI data. In particular, it shows the pharmacokinetic models for the quantification of dynamic contrast enhanced MRI data and my results of the application of the Tofts, the extended Tofts, the shutter speed and the extended shutter speed models on a dataset of patients with brain glioma. - Chapter 4 introduces the multiparametric imaging techniques, in particular the combined PET/CT and the hybrid PET/MRI systems. The last part of the chapter shows the applications of perfusion quantification techniques on a multiparametric study of breast tumour patients, who simultaneously underwent DCE-MRI and 18F-FDG PET on a hybrid PET/MRI scanner. Then the results of a predictive study on the same dataset of breast tumour patients integrated with immunohistochemical markers. Furthermore, the results of a multiparametric study on DCE-MRI and 18F-FCM brain data acquired both on a PET/CT scanner and on an MR scanner, separately. Finally, it will show the application of kinetic analysis in a radiomic study of patients with prostate cancer

CO2 fluxes of Opuntia ficus-indica Mill. trees in relation to water status

Gas exchange pattern in O. ficus-indica(OFI), refers to the Crassulacean Acid Metabolism (CAM); trees have nocturnal stomata opening, so net CO2 uptake and water loss occur during the cooler part ofthe 24-hour cycle. Succulent cladodes skip severe periods of drought through their water storer tissue (parenchyma). To study carbon fluxes in stress and no stress conditions, an experiment was carried out on 3-year-old irrigated and non-irrigated OFI potted trees; whole tree gas exchange was measured continuously with a balloon system made up by a portable Infrared Gas Analyzer. Continuous measurements(nighttime) during the summer season were useful to assess differences in carbon uptake under stress and no stress conditions. There was a gradual increment (5 μmol m2 s-1in June, 7 μmol m2 s-1 in July and 8.8 μmol m2 s-1 in August) in terms of CO2 uptake in irrigated trees from June to August 2010. The uptake was lower in stressed trees than in irrigated ones in each measurements date. Measurements carried out on non-irrigated trees showed carbon gain even 60 days after irrigation was stopped, with less than 2% of soil water content, far below the wilting point. Considering an average of 6.9 μmol CO2 m2 s-1, for well watered trees, from June to August, and a stem area index (SAI) of 2, a daily amount of 21.8 kg ha-1 d-1 of CO2 was accumulated in irrigated trees in that period, corresponding to a carbon assimilation of 0.54 T ha-1