The ecology and control of Opuntia Aurantiaca in South Africa in relation to the cochineal insect, Dactylopius Austrinus

The cochineal insect Dactylopius austrinus De Lotto, which was released on jointed cactus, Opuntia aurantiaca Lindley, in South Africa in 1932, failed to bring the weed under an acceptable level of control in spite of the encouraging results during the first few years after release. The reasons for this apparent failure were never clearly understood. In 1957 the State embarked on an intensive herbicidal control programme which is still in force today. This sustained and expensive programme has undoubtedly reduced the density of the weed in most areas but has failed to solve the problem and the plant continues to expand its range. The biological control of o. aurantiaca in South Africa has been fundamentally influenced by this chemical control campaign. The relationship between chemical and biological control methods is reported in this study

A Concept for Crystal Structure Determination without FOURIER Inversion: Some Steps towards Application

Determination of a crystal structure without Fourier calculation of the scattering density (thus also avoiding the phase problem) is achieved in a fractional coordinate parameter space of dimension 3m where m is the number of independent atoms, reduced to equal point scatterers at rest. For demonstration of the basic ideas, two-dimensional parameter spaces (representing, e. g., one-dimensional two-atom structures) are used. "Central reciprocal lattice row" reflections allow for solving one-dimensional projections of the structure, each requiring less reflections and simultaneously providing better resolution than does a corresponding Fourier summation. The projection solution can be obtained either from the common intersection of the hyper-faces in the m-dimensional parameter space defined by the chosen scattering amplitudes or by exploring the permitted "solution region(s)" that follow from the mere ranking of these amplitudes. All possible solutions satisfying the data are found, including "false minima". The reconstruction of a hypothetical three-dimensional 11 atom structure from the solutions of one-dimensional projections is illustrated in an example based on "theoretical", i. e. error-free data. Since most of the theoretical background is laid down in two former, refereed publications, emphasis is put on different options to cope with the computing demands in practical applications. Advantages and shortcomings of the concept are discussed

Intact procedural motor sequence learning in developmental coordination disorder

The purpose of the present study was to explore the possibility of a procedural learning deficit among children with developmental coordination disorder (DCD). We tested 34 children aged 6–12 years with and without DCD using the serial reaction time task, in which the standard keyboard was replaced by a touch screen in order to minimize the impact of perceptuomotor coordination difficulties that characterize this disorder. The results showed that children with DCD succeed as well as control children at the procedural sequence learning task. These findings challenge the hypothesis that a procedural learning impairment underlies the difficulties of DCD children in acquiring and automatizing daily activities. We suggest that the previously reported impairment of children with DCD on the serial reaction time task is not due to a sequence learning deficit per se, but rather due to methodological factors such as the response mode used in these studies.Peer reviewe

Global Actions for Managing Cactus Invasions

The family Cactaceae Juss. contains some of the most widespread and damaging invasive alien plant species in the world, with Australia (39 species), South Africa (35) and Spain (24) being the main hotspots of invasion. The Global Cactus Working Group (IOBC GCWG) was launched in 2015 to improve international collaboration and identify key actions that can be taken to limit the impacts caused by cactus invasions worldwide. Based on the results of an on-line survey, information collated from a review of the scientific and grey literature, expertise of the authors, and because invasiveness appears to vary predictably across the family, we (the IOBC GCWG): (1) recommend that invasive and potentially invasive cacti are regulated, and to assist with this, propose five risk categories; (2) recommend that cactus invasions are treated physically or chemically before they become widespread; (3) advocate the use of biological control to manage widespread invasive species; and (4) encourage the development of public awareness and engagement initiatives to integrate all available knowledge and perspectives in the development and implementation of management actions, and address conflicts of interest, especially with the agricultural and ornamental sectors. Implementing these recommendations will require global co-operation. The IOBC GCWG aims to assist with this process through the dissemination of information and experienc

Effect size measures and their relationships in stroke studies

No abstract available

PONTOS QUÂNTICOS AMBIENTALMENTE AMIGÁVEIS: DESTAQUE PARA O ÓXIDO DE ZINCO

Semiconductor nanocrystals with sizes in the quantum confinement regime (2-10 nm) present special physical and chemical properties. Additionally, environment-friendly quantum dots (QDs), as zinc oxide and zinc sulfide, offer many practical usages. Herein the ZnO semiconductor nanocrystals properties will be preferentially explored, such as its luminescence, broad spectrum UV absorber and electronics performances, and therefore its multifunctionality, as well as its advantages compared to some toxics QDs. A review is carefully presented stressing some synthesis approaches for applications reasons toward devices, chemosensors, biological labels, UV-absorbers and photocatalysis. ZnO QDs have been used in combination with organic and other inorganic materials. Hybrid materials have many advantages compared to their individual contents leading to important contributions to science and technology. As a result, an important growth in material fields is noticeable