The Impact of Using a Distance Learning Network on Building Teachers' Communities of Practice in Egypt

This research is a case study of using a distance learning network for teachers’ professional development in Egypt. It aims to investigate the impact of using Egypt’s National Network for Distance Training (NNDT) in developing teachers’ knowledge and on building communities of practice. It explores the role of professional development experts and teachers’ participation within the network. In addition, it draws attention to the teachers’ level of engagement in professional development programmes and, therefore, it reveals their modes of participation within the network. Moreover, it identifies the role of the technology in facilitating communication and collaboration between participants. Finally, this paper offers a number of recommendations that aim to develop the network capabilities to become a more ‘effective’ means for teachers’ professional development in Egypt

The Role of Professional Development Networks in Reforming Mathematics Education in Egypt

Mathematics is considered to be one of the key areas for growth and development in Egyptian schools (Monk et al., 1999). Therefore, reforming mathematics education has been given priority by the Egyptian Ministry of Education. Accordingly, a particular emphasis has been given to the professional development of mathematics teachers. This paper is a case study of the role of the Egyptian National Network for Distance Training (NNDT) in development of mathematics teachers’ knowledge and in reforming teachers’ practice in schools. This paper concludes with some suggestions for the effective use of the network in teachers’ professional development

The Effect of Spatial Correlations on Merger Trees of Dark Matter Haloes

The effects of spatial correlations of density fluctuations on merger histories of dark matter haloes (so-called `{\it merger trees}') are analysed. We compare the mass functions of dark haloes derived by a new method for calculating merger trees, that proposed by Rodrigues \& Thomas (RT), with those given by other methods such as the Block model, the Press-Schechter formula and our own formula in which the mass functions are analytically expressed in a way that takes into consideration the spatial correlations. It is found that the mass functions given by the new method are well fit by those given by our formula. We believe that new method (RT) {\it naturally} and correctly takes into account the spatial correlations of the density fluctuations due to a calculated, grid-based realisation of the density fluctuations and so is very useful for estimating the merger tree accurately in a way that takes into consideration spatial correlations. Moreover, by applying our formula, we present an analytic expression which reproduces the mass function derived by the Block model. We therefore show clearly why and how the mass functions given by the new method and the Block model are different from each other. Furthermore, we note that the construction of merger trees is sensitive to the criterion of collapse and merging of overlapped haloes in cases in which two or more haloes happen to overlap. In fact, it is shown that the mass function is very much affected when the criterion of overlapping is changed.Comment: Submitted to MNRAS; 10 pages MN latex file, including 5 figures (epsf

Astrometric mock observations for determining the local dark matter density

To determine the local dark matter density (LDMD) of the solar system is a classical problem in astronomy. Recently, a novel method of determining the LDMD from stellar distribution and vertical velocity dispersion profiles perpendicular to the Galactic plane was devised. This method has the advantage of abolishing conventional approximations and using only a few assumptions. Our aims are to carefully scrutinize this method and to examine influences by uncertainties of astrometric observations. We discuss how the determinations of the LDMD vary with observational precisions on parallax, proper motion, and line-of-sight velocity measurements. To examine the influences by the observational imprecision, we created mock observation data for stars that are dynamical tracers based on an analytical galaxy model and applied parametrized observational errors to the mock data. We evaluated the accuracy of determining the LDMD by applying the method to the mock data. In addition, we estimated a sample size and observational precision required to determine the LDMD with accuracy. We find that the method is capable of determining the LDMD with accuracy if the sample size and observational precisions are satisfactory. The random errors of parallaxes and proper motions can cause systematic overestimation of the LDMD. We estimate the required precisions of the parallax measurements to be approximately 0.1-0.3 milliarcseconds at 1 kpc away from the Sun; the proper motion precisions do not seem to be as important as the parallaxes. From these results, we expect that using the Hipparcos catalog would overestimate the LDMD because of the imprecise parallax measurements if this method is applied; however, we emphasize the capability of the method. We expect that Gaia will provide data precise enough to determine the LDMD.Comment: 16 pages, 14 figures, A&A accepte

Algebraic properties of some varieties of central loops

Isotopes of C-loops with unique non-identity squares are shown to be both C-loops and A-loops. The relationship between C-loops and Steiner loops is further studied. Central loops with the weak and cross inverse properties are also investigated. C-loops are found to be Osborn loops if every element in them are squares.Comment: 20 page

The Saudi Securities Law: Regulation of the Tadawul Stock Market, Issuers, and Securities Professionals under the Saudi Capital Market Law of 2003

On July 31, 2003, the late King Fahd of Saudi Arabia issued Royal Decree number M/3, officially announcing the constitutive law of the securities industry, the Capital Market Law, and leading the Saudi Kingdom into new territory: capital market regulation. For Saudi businessmen, as well as many attorneys, the question “what are securities laws?” is a fair one. Securities laws are the body of rules that regulate certain subjects and issues pertinent to trade in securities, such as the registration and listing of companies in the stock market, securities professionals, the operation of the securities markets, the regulation of investment companies, and public offering of stock. Despite the fact that almost nine years have passed since the enactment of the Capital Market Law, not one comprehensive legal paper has been submitted to explain or discuss the law. This Article attempts to do so by outlining the law of securities relating to securities professionals as laid out in the Capital Market Law and other statutes. Professionals’ fiduciary duties and other legal obligations imposed, such as their duties to the market and their clients, are extensively discussed. Moreover, this article gives a detailed account of the process of offering stock in the Saudi market. Cite as: 18 Annl. Survey Int\u27l. Comp. L. 115 (2012)