University of Lleida

About: University of Lleida is a education organization based out in Lleida, Spain. It is known for research contribution in the topics: Population & Pregnancy. The organization has 2939 authors who have published 5853 publications receiving 148417 citations. The organization is also known as: Escola Superior Politècnica & Universitat de Lleida.

Multivariate analysis of maturity stages, including quality and aroma in `Royal Glory' peaches and `Big Top' nectarines

Abstract: Ethylene production, quality attributes and aroma compounds were analysed to determine the maturity evolution of ‘Big Top’ nectarines and ‘Royal Glory’ peaches at harvest dates ranging from 89 to 116 days after full bloom (DAFB) for nectarines and from 85 to 112DAFB for peaches. These cultivars are highly coloured even in the early stages of maturity. However, the two cultivars had different patterns of ethylene production, this being slower in nectarines than in peaches. Principal component analysis (PCA) was used to provide partial visualisation of the complete data set in a reduced dimension plot. Separation of the two cultivars can be shown by means of a two-dimensional plot of the samples. Although only some aroma compounds are slightly correlated with quality parameters, when aroma volatiles were included in the PCA, the aroma compound set allowed both cultivars to be classified into three stages of maturity: immature, intermediate and fully mature. Compounds such as propanol, hexyl acetate, 2-methylpropyl acetate, limonene, butanol, (Z)-3- hexenyl acetate, buthyl acetate, linalool, ethanol, propyl acetate and ethyl acetate are the most important volatiles for ‘Big Top’ nectarines. It is suggested that the presence of these compounds can be used to indicate when the fruit should be harvested. The presence of g-decalactone, d-octalactone, g-octalactone, ethyl butyrate, hexanal and (E)-2-hexenol can be used to indicate the harvesting maturity stage for ‘Royal Glory’ peaches. The optimum maturity date for harvest would be 105– 107DAFB for ‘Big Top’ nectarines and 93–95DAFB for ‘Royal Glory’ peaches.

The SAT problem of signed CNF formulas

Abstract: Signed conjunctive normal form (signed CNF) is a classical conjunctive clause form using a generalised notion of literal, called signed literal.A signed literal is an expression of the form S:p, where p is a classical atom and S, its sign, is a subset of a domain N.The informal meaning is “p takes one of the values in S”.Signed formulas are a logical language for knowledge representation that lies in the intersection of the areas constraint programming (CP) many-valued logic (MVL), and annotated logic programming (ALP). This central role of signed CNF justifies a detailed study of its subclasses including algorithms for and complexities of associated satisfiability problems (SAT problems). Although signed logic is used since the 1960s, there are only few systematic investigations of its properties. In contrast to work done in ALP and MVL, our present work is a more fine-grained study for the case of propositional CNF. We highlight the most interesting lines of current research: (i) signed versions of some main proponents of classical deduction systems including non-trivial refinements having no classical counterpart; (ii) incomplete local search methods for satisfiability checking of signed formulas; (iii) phase transition phenomena as known, for example, from classical SAT and the influence of the cardinality of N on the crossover point; (iv) the complexity of the SAT problem for signed CNF and its subclasses.

Wheat Yield as Affected by Length of Exposure to Waterlogging During Stem Elongation

Abstract: Waterlogging, if occurring within the stem elongation period (SE), is particularly critical for yield determination. We quantified for the first time the effect of waterlogging duration during SE on yield and studied whether the effects were only direct on resource capture or whether there were feed-forward effects as well. We grew wheat (cv. Soissons) outdoors in long tubes (1.25 m deep) forming a normal canopy and imposed different treatments in SE to finish simultaneously around anthesis (0, 4, 8, 12, 16, 20 and 24 days) plus two complementary treatments (8 and 16 days) starting 10 days after the onset of SE. Yield was reduced linearly with the duration of waterlogging c. 2 % dwaterlogging−1. Treatments mainly affected pre-anthesis spike growth reducing the number of fertile florets and grains, not affecting fruiting efficiency. The magnitude of grain number loss was inversely proportional to the hierarchy of the spikes and spikelets. Grain weight was more marginally reduced, likely through the effects on the size of the ovaries of the developing florets. This reveals a direct effect of waterlogging on the capture of resources with no major feed-forward effects. Losses were in agreement with those from other studies for particular durations of waterlogging.