The Spectral Theory of Perturbative Decays

In this paper, we propose a complex approach to evaluate a function sum of two noncommuting non Hermitian operators. Then, it is proposed an explicit expansion of the evolution operator in the case of the neutral K-meson system under the influence of an external interaction. Then, the importance of the procedure is pointed out to consider the algebraic expansion of the time evolution operator whenever the dynamics decouples the internal transitions and the center of mass motion.Comment: 13 pages, TeX fil

Sustainability in energy production

The requirement of energy in different human activities is continuously increasing; from the energetic production, chiefly by thermal systems, important and worrying environmental problems are generated: there are concerns about climate change, local air quality worsening, exhaustion of resources and land use change. To limit these negative aspects, policies of reduction in energy use must be first proposed; besides different technological, economic and planning solutions can be considered; their effect must be carefully assessed, as concerns effectiveness and practical implementation. The final political decision must consider the different tools that are at disposal, in order to define the best approach for the satisfaction of necessities with the minimum consequent impact

The Classical Analogue of CP-violation

The phenomenological features of the mixing in the neutral pseudoscalar mesons K0-K0bar can be illustrated in the classical framework of mechanics and by means of electromagnetic coupled circuits. The time-reversed not-invariant processes and the related phenomenon of CP-nonconservation can be induced by dissipative effects which yield a not vanishing imaginary part for the relevant Hamiltonian. Thus, two coupled dissipative oscillators can resemble the peculiar asymmetries which are so common in the realm of high energy particle physics.Comment: 12 pages, Latex, 2 figures available by fa

Exploring the metabolic potential of Penicillium rubens

Fungal secondary metabolites are a wide range of chemical molecules with interesting properties for human applications. Although several metabolites are already used in medicine, agriculture and industry, novel molecules based on unique chemical scaffolds are needed to tackle the challenges of society, such as the increasing antimicrobial resistance.Here, we investigated the secondary metabolism of Penicillium rubens, which is used in industry for the production of β-lactam antibiotics. We elucidated a complex and highly branched pathway responsible for the biosynthesis of the yellow pigment chrysogine, by assigning each cluster gene to biosynthetic steps and metabolic intermediates. Moreover, we explore the potential of this fungus as a platform for the production of heterologous valuable secondary metabolites. The strategies and tools established in this work provide the basis for awakening silent gene clusters and engineering biosynthetic pathways, which could lead to the discovery and development of novel molecules with new biological activities

Non-linear principal component analysis (approximation by a second-order Taylor series)

Linear Principal Component Analysis (LPCA) has been applied in multivariate analysis because of its many optimality properties. However, when applied to locate singularities in a set of data, LPCA is only able to locate linear singularities. If the problem being considered tends to produce variables with non-linear relationships, such as with non-linear regression, LPCA is necessarily of limited utility in identifying singularities. Non-linear generalizations of PCA have been suggested in the literature. Essentially, these involve augmenting the data with higher-order terms, in particular square and cross product terms, and running a LPCA on the augmented data set. The problem with this approach is that the fundamental property of parsimony is violated because the number of principal components is greater than the number of original variates. Further, the dimensionality of the augmented data set increases quadratically with respect to the number of original variates. This greatly increases the computational load for practical-sized problems. A new method is proposed in this thesis. It involves writing the general non-linear model as a Taylor Series and truncating after the second-order terms. The data are centered about their means, and the square and cross-product values are computed. The covariance matrix for the augmented problem is computed. The non-linear singularities (or near singularities) are obtained by running a canonical regression using the \u27original and added sets as partitions. The advantage here is that no more principal components may be extracted here than there are variates in the original data set, so the principle of parsimony is upheld. The results of two computational experiments are discussed

Distance Learners: Not Necessarily Distant

The following paper was presented at the 2002 SELA/South Carolina Library Association Joint Conference in Charleston, South Carolina, as part of the “New Voices” program, sponsored by the University and College Libraries Section (UCLS) of SELA. The Southeastern Librarian is pleased to reprint the paper in its entirety. The purpose of this paper is to examine many of the issues involved in providing library services to distance learners, and to discuss the growing overlap of services for traditional on-campus students and distance learners. Is the distinction between the two groups enough to merit a separation of services, or should libraries simply strive to meet the needs of all patrons, regardless of status or qualification? At some schools with a wide variety of course-delivery methods and a large student population, it might be considered a waste of time to differentiate between the distance learner and traditional student, or it might be increasingly difficult to identify the many categories of students. For this reason, it is proposed that libraries begin to consider blending distance library services with traditional services

Trout

The fish is a vessel: cartilage, some bone