Discussing a teacher MKT and its role on teacher practice when exploring data analysis

This article considers teacher knowledge in managing mathematically critical situations and the role of what can be termed a mathematical summary in the analysis of a teaching episode, viewed from the perspective of Mathematical Knowledge for Teaching (MKT). The analysis is based on an episode of content review, from a perspective which aims to understand the teacher’s logic rather than merely identify gaps in their knowledge. We discuss the importance of approaching mathematically critical situations in order to contribute to eradicating mathematical innumeracy (statistics) and to promote a kind of practice which is “mathematically demanding” as well as “pedagogically exciting”

Security Policy Consistency

With the advent of wide security platforms able to express simultaneously all the policies comprising an organization's global security policy, the problem of inconsistencies within security policies become harder and more relevant. We have defined a tool based on the CHR language which is able to detect several types of inconsistencies within and between security policies and other specifications, namely workflow specifications. Although the problem of security conflicts has been addressed by several authors, to our knowledge none has addressed the general problem of security inconsistencies, on its several definitions and target specifications.Comment: To appear in the first CL2000 workshop on Rule-Based Constraint Reasoning and Programmin

The Impacts of Structural Changes in the Labor Market: a Comparative Statics Analysis Using Heterogeneous-agent Framework

In this paper we aim at analyzing the impacts on welfare and wealth and consumption distribution across different labor market structural features. In particular, we pursue a steady-state analysis to assess the impacts of unit vacancy costs, unemployment replacement ratio or the job destruction rate, when they are changed in order to promote a given reduction in the unemployment rate. We combine a labor market search and matching framework with unions, based on Mortensen and Pissarides (1994) with a heterogeneous-agent framework close to Imrohoroglu (1989) in a closed economy model. Such approach enables the joint assessment of macroeconomic welfare and inequality together with implications derived from institutional changes in labor market. Moreover, the transition matrix between worker's states is endogenous, fully derived from labor market conditions. Using feasible calibration to the Euro Area, we conclude that different institutional changes to promote unemployment reduction have non-neutral and differentiated effects on welfare and inequality. While changing unit vacancy costs and job destruction can be ranked, changes in the unemployment benefit replacement ration involve a trade-off between gains in welfare and in consumption/income distribution.Labor market institutions, search and matching models, heterogeneous-agent models, welfare and inequality.

Admissão à carreira de Oficial do Quadro Permanente da Força Aérea

É através da admissão à carreira de Oficial do Quadro Permanente que a Força Aérea Portuguesa vai recrutar os futuros oficiais do seu Quadro Permanente, daí a importância de se analisar os procedimentos actuais da admissão, de forma a investigar novos elementos com o objectivo de introduzir mais valias para o melhoramento de tão importante e delicado processo, contribuindo para uma optimização dos procedimentos e da qualidade dos recursos humanos recrutados. Assim, realizou-se um enquadramento da situação actual relativamente à admissão dos oficiais ao Quadro Permanente da Força Aérea Portuguesa, pela via do Curso em Ciência Militares Aeronáuticas e pela via dos Estágios Técnicos-Militares da Academia da Força Aérea. Posteriormente e, na sequência da investigação realizada e das entrevistas efectuadas, analisaram-se propostas com o objectivo de contribuir para a optimização dos procedimentos supra-enunciados, que nos permitiram validar as hipóteses desenhadas. Abstract: It is through the admission to the Permanent Staff Officers’ Course, in the Air Force Academy, that the Portuguese Air Force recruits its future officers. Consequently, it is important to analyze the current admission procedures in order to investigate if there are new elements to be introduced that may add more value to this important and delicate process. By making the process better, this research will contribute to the procedure optimization and to the quality of the recruited human resources. Initially, there is a framework of the current situation regarding the admission to the officers’ permanent staff in the Portuguese Air Force, considering both the Military Science Courses and the Technical-Military Training in the Air Force Academy. Subsequently, following the research and some interviews and after validating the initial assumptions, proposals are made with the aim of contributing to the optimization of the above-mentioned procedures

Epigenetic events underlying somatic cell reprogramming

Although differentiated cells normally retain cell-type-specific gene expression patterns throughout their lifetime, cell identity can sometimes be modified or reversed in vivo by transdifferentiation, or experimentally through cell fusion or by nuclear transfer. Several studies have illustrated the importance of chromatin remodelling, DNA demethylation and dominant transcriptional factor expression for changes in lineage identity. Here the epigenetic mechanisms required to “reset” genome function were investigated using experimental heterokaryons. To examine the epigenetic changes that are required for the dominant conversion of lymphocytes to muscle, I generated stable heterokaryons between human B-lymphocytes and mouse C2C12 myotubes. I show that lymphocyte nuclei adopt an architecture resembling that of muscle and initiate the expression of musclespecific genes in the same temporal order as developing muscle. The establishment of this novel gene expression program is coordinated with the shutdown of several lymphocyte-associated genes. Interestingly, inhibition of histone deacetylase (HDAC) activity during reprogramming selectively blocks the silencing of lymphocyte-specific genes but does not prevent the establishment of muscle-specific gene expression. In order to reprogram somatic cells to pluripotency, I fused human Blymphocytes and mouse embryonic stem (ES) cells. The conversion of human cells is initiated rapidly, occurring in heterokaryons before nuclear fusion. Reprogramming of human lymphocytes by mouse ES cells elicits the expression of a human ES-specific gene expression profile in which endogenous hSSEA4, hFgf receptors and ligands are expressed while factors that are characteristic of mouse ES cells, such as Bmp4 and Lif receptor are not. Using genetically engineered mouse ES cells I demonstrate that successful reprogramming requires the expression of Oct4, but importantly, does not require Sox2, a factor implicated as critical for the induction of pluripotency. Following reprogramming, mOct4 becomes dispensable for maintaining the multi-potent state of hybrid cells. Finally, I have examined the reprogramming potential of embryonic germ (EG), embryonic carcinoma (EC) and ES cells deficient for the Polycomb repressive complex 2 (PRC2) proteins Eed, Suz12 and Ezh2. While EC and EG cells share the ability to reprogram human lymphocytes with ES cells, the lack of Polycomb proteins abolishes reprogramming. Thus, the repressive chromatin mark (H3K27 methylation) catalysed by PRC2 play a crucial role in keeping ES cells with full reprogramming capacity. Collectively my results underscore the importance of chromatin events during cell fate reprogramming

Production and characterization of activated carbons made from sunflower stems

Activated carbons (ACs) are artificial materials, prepared from natural or synthetic precursors that are worldwide extensively used. The ACs main characteristics are the noticeable adsorption capabilities provided by the highly developed porous structure and the rich surface chemistry. Because of their versatility and properties the final material can be tailored to have specific properties suitable for a wide range of applications such as medical uses, gas storage, removal of pollutants and odours, gas separation and purification as well as in catalysis. With the increase of activated carbon demand, one of the main challenges lies in the attempt to find new precursors, which are cheap and accessible with good valorisation potential, like industrial and agricultural residues. In the present work we report the production of ACs from sunflower stems, an agricultural by-product, through a physical activation process by CO2 and H2O, using a single step carbonisation at 400ºC, which as far as it came to our knowledge was never made for this precursor