A Compact Codimension Two Braneworld with Precisely One Brane

Building on earlier work on football shaped extra dimensions, we construct a compact codimension two braneworld with precisely one brane. The two extra dimensions topologically represent a 2-torus which is stabilized by a bulk cosmological constant and magnetic flux. The torus has positive constant curvature almost everywhere, except for a single conical singularity at the location of the brane. In contradistinction to the football shaped case, there is no fine-tuning required for the brane tension. We also present some plausibility arguments why the model should not suffer from serious stability issues.Comment: 13 pages, 2 figures; references added, typos fixes; essentially the version published in PR

A comparison between the contexts learners in Grades 8, 9 and 10 prefer for mathematical literacy and gender

Magister Educationis - MEdFor many years, there have been calls for the mathematics curriculum in South African schools to be made more meaningful and relevant to young people's everyday lives. Despite efforts to address this issue, there is a widespread perception wihtin the mathematics education community that much remains to be seen. Broadly, this study focused on the contexts preferred by grade 8 , 9 and 10 learners as a domain in which to embed mathematics. The particular focus was on whether gender played a role in the preferences expressed by these learners for contexts.South Afric

Assessment of Sustainable Development

The objective of this paper is to introduce fuzzy set theory and develop fuzzy mathematical models to assess sustainable development based on context-dependent economic, ecological, and societal sustainability indicators. Membership functions are at the core of fuzzy models, and define the degree to which indicators contribute to development. Although a decision-making process regarding sustainable development is subjective, fuzzy set theory links human expectations about development, expressed in linguistic propositions, to numerical data, expressed in measurements of sustainability indicators. In the future, practical implementation of such models will be based on elicitation of expert knowledge to construct a membership function. The fuzzy models developed in this paper provide a novel approach to support decisions regarding sustainable development.agriculture;assessment;fuzzy set theory;sustainable development

Stable divisorial gonality is in NP

Divisorial gonality and stable divisorial gonality are graph parameters, which have an origin in algebraic geometry. Divisorial gonality of a connected graph $G$ can be defined with help of a chip firing game on $G$. The stable divisorial gonality of $G$ is the minimum divisorial gonality over all subdivisions of edges of $G$. In this paper we prove that deciding whether a given connected graph has stable divisorial gonality at most a given integer $k$ belongs to the class NP. Combined with the result that (stable) divisorial gonality is NP-hard by Gijswijt, we obtain that stable divisorial gonality is NP-complete. The proof consist of a partial certificate that can be verified by solving an Integer Linear Programming instance. As a corollary, we have that the number of subdivisions needed for minimum stable divisorial gonality of a graph with $n$ vertices is bounded by $2^{p(n)}$ for a polynomial $p$

Dose- and Time-Dependent Increase of Lysosomal Enzymes in Embryonic Cartilage in Vitro after Ionizing Radiation

Radiation doses of 20, 50 or 100 Gy caused the same time related decrease for RNA and proteoglycan (PG) synthesis in embryonic cartilage in vitro (4 days culture). In this paper, participation of lysosomes in this radiation response is investigated. Therefore, we employ a cytochemical method using -glycerophosphate as substrate for acid phosphatase (AP) detection. Increase of AP was found 2 days after irradiation and increased during the whole culture period. The increase was more pronounced with a higher radiation dose. Stimulation of AP activity explains the observed radiation response of RNA and PG synthesis

Key physicochemical characteristics governing organic micropollutant adsorption and transport in ion-exchange membranes during reverse electrodialysis

The co-generation of electricity and electrodialysis of seawater in a hybrid system is a promising approach to overcome water scarcity. Reverse electrodialysis harvests energy from the salinity gradient, where seawater is used as a high salinity stream while secondary treated wastewater can be used as a sustainable low salinity stream. Treated wastewater contains organic micropollutants, which can be transported to the seawater stream. The current research establishes a connection between adsorption and transport of organic micropollutants in ion exchange membranes, using a cross-flow stack in adsorption and zero-current experiments. To mimic the composition of treated wastewater, a mixture of nineteen organic micropollutants of varied physicochemical characteristics (e.g. size, charge, polarity, hydrogen donor/acceptor count, hydrophobicity) at environmentally relevant concentrations was used. Depending on the charge, micropollutants develop different types of mechanisms responsible for short-distance interactions with ion-exchange membranes, which has a direct influence in their transport behavior. This study provides a rational basis for the optimization/design of next-generation ion-exchange membranes, in which the permeability toward organic micropollutants should be also included. This investigation highly contributes to understanding the potential hazard posed by organic micropollutants in reverse electrodialysis in seawater desalination systems, where treated wastewater is used as a low salinity stream

The sense of it all: Framing and narratives in sensegiving about a strategic change

Managers leading strategic change processes have to be skilled language users in order to convince others of the necessity of change and to shape the interpretations of their followers in a preferred direction. This paper asks how and why managers employ certain forms of language in their sensegiving during strategic change, and when these managers are effective in their language use to change the sensemaking of others in the organization. On the basis of a longitudinal case study of a European multinational corporation, we find that effective sensegiving is about providing organizational members with a pragmatic form – a way of making sense rather than, as previous research suggests, about providing them with pre-packaged meanings. We extend prior research by distinguishing the effects that the different linguistic forms of managerial sensegiving have on organizational sensemaking. Furthermore, the managers we studied were effective in their sensegiving when they combined framing and narratives. These two forms of language supported each other by amplifying the overall effect on organizational sensemaking. This notion of a combined use of framing and narratives complements previous research, which has largely studied them separately

The sense of it all: Framing and narratives in sensegiving about a strategic change

Managers leading strategic change processes have to be skilled language users in order to convince others of the necessity of change and to shape the interpretations of their followers in a preferred direction. This paper asks how and why managers employ certain forms of language in their sensegiving during strategic change, and when these managers are effective in their language use to change the sensemaking of others in the organization. On the basis of a longitudinal case study of a European multinational corporation, we find that effective sensegiving is about providing organizational members with a pragmatic form – a way of making sense rather than, as previous research suggests, about providing them with pre-packaged meanings. We extend prior research by distinguishing the effects that the different linguistic forms of managerial sensegiving have on organizational sensemaking. Furthermore, the managers we studied were effective in their sensegiving when they combined framing and narratives. These two forms of language supported each other by amplifying the overall effect on organizational sensemaking. This notion of a combined use of framing and narratives complements previous research, which has largely studied them separately