The influence of genome size and limitation of nitrogen and phosphorus on photosynthesis efficiency

Genome size varies 2,400-fold in angiosperms and is an important trait influencing cellular and physiological parameters. One of the major drivers of the astonishing genome size (GS) diversity in angiosperms is polyploidisation and most flowering plant lineages have undergone multiple rounds of polyploidy in their ancestry. Because of the frequency of ancestral polyploidy, one might expect angiosperm genomes to be larger than other eukaryotes, where polyploidy is less frequent. But this is not the case, where GS in angiosperms is skewed towards small genomes, suggesting that, following polyploidy, there is selection over time to reduce GS. It is possible that one selection pressure that acts to reduce the size of the genome is the efficiency of photosynthesis, which may be enhanced in species with small genome sizes. This is because there is a positive correlation between the size of the nucleus and the guard cells across species, which can in turn influence the rate of gas exchange through stomata pores. Photosynthesis may also be influenced by nitrogen (N) and phosphorus (P) availability. These macronutrients are limiting nutrients to plants and play an important role for them, because they are the main constituents of the nucleic acids and they play crucial role in photosynthesis in many processes. Nitrogen is needed to build photosynthetic proteins, but especially for the RuBisCO enzyme and chlorophylls, which are N demanding. Phosphorus is used as ATP and NADPH to give the chemical energy necessary for the fixation of CO2. Both these N and P demands for photosynthesis may compete with the N and P demands of the nucleus, which may be higher in species with large genomes than species with smaller genomes. Thus in considering the selection constraints on genome size in plants it is necessary to consider the effects of GS and nutrient availability on photosynthesis. The overall aim of this PhD project is to determine how GS and nutrient availability impacts photosynthesis. To do that three experimental systems are exploited. These are: (1) The effects of GS on the efficiency of photosynthesis in plant genus Fritillaria, selected because it has particularly large genome sizes, and it has the largest range in genome size, all at the diploid level, for any genus (70 Gb/1C range). These materials enable determination of the impact of GS on cell size, gas exchange and light harvesting properties of photosynthesis. Surprisingly, no effect of GS on cell size 5 was observed, contrary to published expectation, but there was a significant correlation between GS and photosynthesis readings. (2) The effects of GS on the efficiency of photosynthesis in plant genus Nymphaea, selected because it has small genome sizes and polyploidy variants. The polyploid variants enable the effect of step changes in GS associated with polyploidy to be determined. This enables the determination of the impact of polyploidy on photosynthesis and to determine the efficiency of photosynthesis across species in an aquatic plant genus. Exceptionally low non-photochemical quenching (NPQ) was observed in these species, indicative of highly efficient light energy use, perhaps associated with small genome sizes overall and an aquatic habit. There was a relationship between GS and cell size in this genus, despite the range of GS being smaller than for Fritillaria. (3) The effect of nutrient availability and photosynthesis in wheat, selected because of its agricultural importance, its large genome size, and relatives at different ploidy levels with which the data could be compared in future studies. This material enables the effects of nutrient limitation on photosynthesis to be determined, and which components of photosynthesis are most impacted. The results revealed that some components of photosynthesis were significantly impacted by P alone (photochemical quenching (qP, negatively), non-photochemical quenching capacity (NPQ, positively)), others by N alone (maximum rate of carboxylation by RuBisCO (Vcmax, negatively)), whilst both N and P limitation and their interactions reduced biomass. The data show that interactions between photosynthesis, N and P and GS play a role in influencing plant biomass. What we now need to know in future studies is if there are N and P trade-offs between the nucleic acid sink represented by the plant genome and proteins and pigments (chlorophyll) needed for photosynthesis. For example, RuBisCO, essential for the dark reaction of photosynthesis, is likely to compete with the nucleic acid sinks for N, whilst metabolic processes, which require for example ATP, NADPH or protein phosphorylation, are likely to compete with the nucleic acid sinks for P

Sensing the impact of COVID-19 restrictions from online reviews: The cases of London and Paris unveiled through text mining

This study aims to understand how the COVID-19 pandemic affected the hotel sector and to identify the current traveler demands. The traveler’s re-views were analyzed based on sentiment analysis and a guest satisfaction model was also proposed, demonstrating a data mining approach within tourism and hospitality research. Given its popularity, TripAdvisor was the chosen platform for collection of hotel reviews in London and Paris. Text data were extracted from reviews made in two time periods, before and during the COVID-19 pan-demic. The sentiment and specific aspects highlighted by travelers were com-pared between each period.info:eu-repo/semantics/acceptedVersio

Towards the Development of Delivery Systems of Bioactive Compounds With Eyes Set on Pharmacokinetics

Delivery systems carrying natural bioactive compounds for enhanced targeting and controlled release are capturing increasing attention. High loadings and sustained release are common design goals. However, in the case of compounds naturally present in human nutrition and physiology, further efforts are justified to optimize their bioactivity and promote clinical success. In this work, it is proposed a specific attention to the regulation of drug temporal presentation as important factor to obtain novel multifunctional delivery systems meeting higher therapeutic efficiencies. Case studies on the relation between drug release dynamics and biological responses are presented for some major delivery strategies and different bioactive molecules. Pharmacokinetic essential concepts and issues concerning the multi-target mode of action typical of the pharmacological properties of natural compounds are discussed in the perspective of improving the development of efficient drug formulations. Several classes of controlled release systems are considered through the chapter, and laboratory setups for testing films and particulate delivery systems are detailed, as well as the application of models for kinetic analysis. Descriptions are illustrated with experimental results obtained with caffeine and epicatechin in our laboratory. Future investigations will benefit from preclinical and clinical evaluation of the new formulations developed by emerging approaches and tools that are being suggested by diverse authors.info:eu-repo/semantics/publishedVersio

Actividade Científica e de Investigação num Hospital Central: Análise Retrospectiva de Dez Anos

Introdução: A actividade científica faz parte do desempenho de um clínico da carreira médica hospitalar e os hospitais centrais devem ser a sede privilegiada da investigação clínica hospitalar. O objectivo do presente trabalho é o de avaliar retrospectivamente a actividade científica e de investigação de um hospital central, o Hospital de Dona Estefânia. Métodos: Foram avaliados, de 1993 a 2002 (dez anos), os resumos do Anuário do Hospital de Dona Estefânia, publicação anual que colige os trabalhos realizados pelo seu corpo clínico. O estudo incluiu a análise do tipo de trabalhos, a sua forma de divulgação e a produção científica, por intermédio da taxa de trabalhos por médico e por área de assistência. Resultados: Nos dez anos em análise foram incluídos 1821 trabalhos científicos, sendo 49.7% de investigação; a produção média anual do Hospital foi de 182 trabalhos, 165 comunicações e 24.5 publicações. Em 2002 foram considerados 312 médicos em 24 áreas de assistência, calculando-se uma razão por médico de 0.73 trabalhos científicos, dos quais 0.29 trabalhos de investigação. Discussão: O Anuário constituiu um excelente instrumento para medição directa da actividade científica e de investigação, abrangendo não só trabalhos publicados, mas também os não publicados. Embora não haja dados nacionais similares para comparação, seria de esperar uma maior produção científica do que a que consta no Anuário, tratando-se de um hospital central. Para tal facto podem ter contribuído a sobrecarga assistencial e o valor exíguo atribuído à actividade científica e, particularmente à investigação, na legislação que regula a contratação do corpo clínico nos hospitais portugueses

Image, satisfaction, destination and product post-visit behaviours: How do they relate in emerging destinations?

This study proposes a conceptual model that sheds light on how the destination image of emerging tourist destinations relates to tourism satisfaction and intention to subsequently recommend the place and purchase its products. Destination image is studied through three components – cognitive, affective, and unique. Unique image has been overlooked in previous research and few studies focus on its measurement. This study uses a new method of measuring it through text-mining of user-generated blog posts. Findings from a sample of 314 foreign visitors to Sofia, Bulgaria, reveal that the affective image influences tourist satisfaction and post-visit behaviour; the cognitive component has a significant effect on all the constructs, except for tourist satisfaction, whereas unique image only influences the intention to recommend and purchase destination country products. Joining together two streams of research, this study also argues that the intention to recommend a destination spot influences the intention to buy its products.This study proposes a conceptual model that sheds light on how the destination image of emerging tourist destinations relates to tourism satisfaction and intention to subsequently recommend the place and purchase its products. Destination image is studied through three components – cognitive, affective, and unique. Unique image has been overlooked in previous research and few studies focus on its measurement. This study uses a new method of measuring it through text-mining of user-generated blog posts. Findings from a sample of 314 foreign visitors to Sofia, Bulgaria, reveal that the affective image influences tourist satisfaction and post-visit behaviour; the cognitive component has a significant effect on all the constructs, except for tourist satisfaction, whereas unique image only influences the intention to recommend and purchase destination country products. Joining together two streams of research, this study also argues that the intention to recommend a destination spot influences the intention to buy its products.info:eu-repo/semantics/acceptedVersio

Solving Linux Upgradeability Problems Using Boolean Optimization

Managing the software complexity of package-based systems can be regarded as one of the main challenges in software architectures. Upgrades are required on a short time basis and systems are expected to be reliable and consistent after that. For each package in the system, a set of dependencies and a set of conflicts have to be taken into account. Although this problem is computationally hard to solve, efficient tools are required. In the best scenario, the solutions provided should also be optimal in order to better fulfill users requirements and expectations. This paper describes two different tools, both based on Boolean satisfiability (SAT), for solving Linux upgradeability problems. The problem instances used in the evaluation of these tools were mainly obtained from real environments, and are subject to two different lexicographic optimization criteria. The developed tools can provide optimal solutions for many of the instances, but a few challenges remain. Moreover, it is our understanding that this problem has many similarities with other configuration problems, and therefore the same techniques can be used in other domains.Comment: In Proceedings LoCoCo 2010, arXiv:1007.083

The ECSI model in higher education in tourism: a segmentation analysis in the Portuguese case

This research explores the European Consumer Satisfaction Index model applied to higher education in tourism by including the construct of employability and by accounting for unobserved heterogeneity. In particular, it intends to identify segments of higher education institutions' (HEI) consumers based on the structural model estimates of the European Consumer Satisfaction Index (ECSI), enlarged with the employability construct. A model-based segmentation approach using FIMIX in PLS path model-ling is used. Th e ECSI is properly adjusted to the educational framework and shows its effectiveness when assessing students' satisfaction regarding the attended HEI. Two distinctive graduate segments are identifi ed using a sample of 166 HEI consumers. The results confi rm the assumption of heterogeneity as the relationships differ across segments and the need for HEIs to target those segments differently in such a competitive context.info:eu-repo/semantics/publishedVersio