Weak covering properties and selection principles

No convenient internal characterization of spaces that are productively Lindelof is known. Perhaps the best general result known is Alster's internal characterization, under the Continuum Hypothesis, of productively Lindelof spaces which have a basis of cardinality at most $\aleph_1$. It turns out that topological spaces having Alster's property are also productively weakly Lindelof. The weakly Lindelof spaces form a much larger class of spaces than the Lindelof spaces. In many instances spaces having Alster's property satisfy a seemingly stronger version of Alster's property and consequently are productively X, where X is a covering property stronger than the Lindelof property. This paper examines the question: When is it the case that a space that is productively X is also productively Y, where X and Y are covering properties related to the Lindelof property.Comment: 16 page

The effect of chiropractic manipulation on the sacroiliac joints compared to mobilisation, on the weight distribution through the lower limbs

Sacro-iliac joint (S.I joint) dysfunction can result in leg length discrepancies (LLD). LLD has been associated with many musculoskeletal problems such as osteoarthritis of the hips, knee pain and lower back pain. It has been theorised that LLD alters a persons body posture, which in turn changes the forces acting on the joints in the lower extremity and spine. These unnatural forces then create the excessive forces seen as the causative factors in the previously mentioned musculoskeletal conditions. (Murrel, Cornwall, Doucet 1991) The purpose of this pilot study was to was to compare the effect of chiropractic manipulative therapy on the S.I joints with chiropractic mobilisations of the S.I joints on the weight transfer from the spine into the lower limbs. This randomised study consisted of two groups of fifteen patients between the ages of eighteen and fifty years. All potential candidates were examined and admitted once all the inclusion and exclusion criteria had been met. Once S.I joint restrictions were detected the patient received either chiropractic manipulation or mobilisation to the restricted joint. Group A received chiropractic manipulation while group B were treated with mobilisations of the S.I joints. Patients were treated over a two week treatment period. Objective measurements were taken before the 1st treatment and after the 1st ,3rd ,5th and final consultations one month later. The measurements were taken with the Spinal Analyses Machine (S.A.M). This instrument has got two scales on a platform that determines the patients weight distribution from the spine through the left and right lower limbs. The data collected was then statistically analysed using the One Way ANOVA Test (analyses of variance) as well as the Student-Newman-Keuls Method to compare the inter-group and intra-group data. Statistically significant changes in the weight distribution between the lower limbs were seen in group A. Based on the results from the study chiropractic manipulation to the S.I joint proved to be more effective than mobilisation in the treatment of S.I joint dysfunction. This does however require further research, and a larger sample size.Dr. M. Moodley Dr. J. Kotz

Etnocentrisme in Nederland: Veranderingen bij kansarme en/of gepriviligeerde groepen?

Contains fulltext : 3309.pdf (publisher's version ) (Open Access

Private Standards, Handling and Hygiene in Fruit Export Supply Chains: A Preliminary Evaluation of the Economic Impact of Parallel Standards

With the emergence of private food safety and quality standards in developed countries fruit exporting countries in the developing world face increasing constraints to access markets in the rich industrialised countries in the North. Producers in the South have no alternative as to make the necessary investments on farms and in pack houses to comply with the requirements of these food quality and safety standards. The export of fresh fruit is an important component of South African agricultural exports, with citrus fruit exported to markets such as Europe being of particular importance. This paper reports selected results from a large research project into the impact of private standard compliance on the quality of the fruit and the returns to farmers. The research process involved a multi-disciplinary analysis of Agricultural Economics and Microbiology / Plant pathology as we analysed the dynamics of the citrus export supply chain from the farms in South Africa to the end consumer in Europe. Sampled fruit containers were followed through the whole supply chain which allowed us to provide an exposé of the behaviour of the different actors in the citrus supply chain and obtain some evidence of poor handling and hygiene standards by means of a comparison of the experimental observations with various relevant components of the EurepGAP control points and compliance criteria for fruit and vegetables. Observations suggest that these standards are adequately applied to the production and handling of fruit at the farm and pack house levels while on the other hand the subsequent stages (mainly after the importing harbour in Europe) of the fruit supply chain are seemingly not subjected to the same strict requirements laid out for producers, leading to fruit quality deterioration and financial losses for producers. This constitutes clear parallel standards in terms of fruit safety and quality standards between upstream and downstream sections of the supply chain and questions thus the purpose of the standards and the financial return for producers making large investments to comply with these privately introduced standards.International Relations/Trade,

Some new directions in infinite-combinatorial topology

We give a light introduction to selection principles in topology, a young subfield of infinite-combinatorial topology. Emphasis is put on the modern approach to the problems it deals with. Recent results are described, and open problems are stated. Some results which do not appear elsewhere are also included, with proofs.Comment: Small update

Using Ciliate Operations to Construct Chromosome Phylogenies

Whole genome sequencing has revealed several examples where genomes of different species are related by permutation. The number of certain types of rearrangements needed to transform one permuted list into another can measure the distance between such lists. Using an algorithm based on three basic DNA editing operations suggested by a model for ciliate micronuclear decryption, this study defines the distance between two permutations to be the number of ciliate operations the algorithm performs during such a transformation. Combining well-known clustering methods with this distance function enables one to construct corresponding phylogenies. These ideas are illustrated by exploring the phylogenetic relationships among the chromosomes of eight fruit fly (Drosophila) species, using the well-known UPGMA algorithm on the distance function provided by the ciliate operations

The combinatorics of the Baer-Specker group

Denote the integers by Z and the positive integers by N. The groups Z^k (k a natural number) are discrete, and the classification up to isomorphism of their (topological) subgroups is trivial. But already for the countably infinite power Z^N of Z, the situation is different. Here the product topology is nontrivial, and the subgroups of Z^N make a rich source of examples of non-isomorphic topological groups. Z^N is the Baer-Specker group. We study subgroups of the Baer-Specker group which possess group theoretic properties analogous to properties introduced by Menger (1924), Hurewicz (1925), Rothberger (1938), and Scheepers (1996). The studied properties were introduced independently by Ko\v{c}inac and Okunev. We obtain purely combinatorial characterizations of these properties, and combine them with other techniques to solve several questions of Babinkostova, Ko\v{c}inac, and Scheepers.Comment: To appear in IJ

Professionals' preferences in prenatal counseling at the limits of viability: a nationwide qualitative Dutch study

Item does not contain fulltextPrenatal counseling practices at the limits of viability do vary, and constructing a counseling framework based on guidelines, professional and parental preferences, might achieve more homogeneity. We aimed to gain insight into professionals' preferences on three domains of counseling, particularly content, organization, and decision making and their influencing factors. A qualitative, nationwide in-depth exploration among Dutch perinatal professionals by semi-structured interviews in focus groups was performed. Regarding content of prenatal counseling, preparing parents on the short-term situation (delivery room care) and revealing their perspectives on "quality of life" were considered important. Parents should be informed on the kind of decision, on the difficulty of individual outcome predictions, on survival and mortality figures, short- and long-term morbidity, and the burden of hospitalization. For organization, the making of and compliance with agreements between professionals may promote joint counseling by neonatologists and obstetricians. Supportive materials were considered useful but only when up-to-date, in addition to the discussion and with opportunity for personalization. Regarding decision making, it is not always clear to parents that a prenatal decision needs to be made and they can participate, influencing factors could be, e.g., unclear language, directive counseling, overload of information, and an immediate delivery. There is limited familiarity with shared decision making although it is the preferred model. CONCLUSION: This study gained insight into preferred content, organization, and decision making of prenatal counseling at the limits of viability and their influencing factors from a professionals' perspective. What is Known: * Heterogeneity in prenatal counseling at the limits of viability exists * Differences between preferred counseling and actual practice also exists What is New: * Insight into preferred content, organization, and decision making of prenatal periviability counseling and its influencing factors from a professionals' perspective. Results should be taken into account when performing counseling. * Particularly the understanding of true shared decision making needs to be improved. Furthermore, implementation of shared decision making in daily practice needs more attention