Syftet med den här undersökningen, var att beskriva vilken betydelse som gruppdiskussioner och laborationerna kan ha för elevers lärandemöjligheter inom ämnet matematik i en åk 8, med ett extra fokus på SUM-elever. Studien gjordes dels med hjälp av systematiska observationer då klassen genomförde fyra laborationer tillsammans med ordinarie matematiklärare, dels med hjälp av tio stycken enskilda kvalitativa intervjuer (varav sex stycken av ungdomarna var SUM-elever) i en åk8 vid en skola i Västerbottens inland. Studien utgick från ett sociokulturellt perspektiv, det kritiska perspektivet på matematiksvårigheter och som analysverktyg användes olika typer av samtal. Resultatet visade på att de flesta eleverna tyckte att både laborationer och gruppdiskussioner ökar deras möjligheter till lärande. Alla informanterna betonade på vikten av att få delta i grupper bestående av deras kamrater då de ansåg att det gav ett bättre samarbete och en mer givande diskussion. Under laborationerna interagerade för det mesta SUM-eleverna med varandra respektive de övriga eleverna med varandra. Största delen av samtalen i grupperna bestod av sådana samtal som erbjuder möjligheter till lärande. Däremot fanns även inslag av samtal vilka inte erbjuder lärandemöjligheter och därmed inte leder till utveckling av ny kunskap. SUM-eleverna i laborationsgrupperna hade inte i lika stor utsträckning som de övriga eleverna tillgång till de typer av samtal som gav större lärandemöjligheter.

Thesis (MSc (Physics))--Stellenbosch University, 2008. / Third harmonic generation (THG) in a metal vapour is a nonlinear optical interaction that facilitates the generation of light in the vacuum ultraviolet (VUV) portion of the electromagnetic spectrum. The requirement of the metal vapour medium is that it has a suitably large third order nonlinear susceptibility. The third order susceptibility is further enhanced by a two photon resonance. Zinc and magnesium vapours are such nonlinear media. The THG process can be phase matched by mixing the metal vapour with a noble gas in a speci c pressure ratio. The metal vapour noble gas mixture needs to be homogeneous and its temperature needs to be constant to within less than a degree Celsius over a path length of 7 cm. These requirements are satis ed by a crossed heat pipe oven. The heat pipe oven makes use of a dynamic liquid-vapour phase equilibrium in sodium in order to maintain a constant temperature of around 800 degrees Celsius, thus facilitating the generation of a stable homogeneous medium of metal vapour and noble gas that can be used for e cient generation of VUV radiation. The development of such a VUV source using zinc vapour and the application of a similar VUV source using magnesium vapour are discussed. The VUV radiation has been applied to laser induced uorescence spectroscopy of carbon monoxide (12C16O and 13C16O). Spectral lines of 20 spin-forbidden singlet-triplet transitions of the e3 − − X1 +(5 0) band were detected and accurate experimental wavelengths determined for the rst time for ve of these lines.

Området för studien är valt utifrån att vi i vår verksamhet som lärare har uppmärksammat elevers svårigheter i huvudräkning. Syftet med interventionsstudien är att undersöka hur räkneflyt i huvudräkning inom talområdet 11-20 i addition och subtraktion kan utvecklas för elever i SUM genom strukturerad undervisning utifrån Wendick-modellen. I studien deltar tre elever i årskurs 4 och två elever i årskurs 7. Metoder som används är huvudräkningstest och intervjuer före samt efter studien. Även loggbok förs under studien. Intensivundervisningen som är vid 4-5 tillfällen i veckan, under 5 veckor utgår från en strukturerad arbetsgång en-en. Under studien uppmärksammas betydelsen av att utgå från elevens förkunskaper, att utveckla elevers taluppfattning och hållbara huvudräkningsstrategier. Resultatet indikerar på att räkneflyt behöver mycket tid för att utvecklas och att strukturerad intensivundervisning under kortare tid har större effekt på räkneflyt hos yngre elever än äldre. En positiv påverkan av intensivundervisning som uppmärksammas är att elevernas motivation ökade under studiens gång.

När man talar om begreppet matematiksvårigheter så finns det många olika tolkningar. Syftetmed denna studie är att få mer kunskap om lärares syn på matematiksvårigheter, samt vilkaresurser som används i undervisningen för elever i matematiksvårigheter i årskurserna 4–6.I denna studie undersöks lärares olika föreställningar och erfarenheter avmatematiksvårigheter genom kvalitativa semistrukturerade intervjuer. Tillsammans medförfattares olika tolkningar av begreppet matematiksvårigheter söks en djupare förståelse förundervisning av elever i matematiksvårigheter. Resultatet visar hur lärare upptäcker elever imatematiksvårigheter samt hur undervisningen anpassas på bästa sätt för dessa elever. Trotslärares olika förutsättningar så tycks de göra ett gediget arbete för att erbjuda elever rätt stöd iundervisningen.

Neste trabalho usamos as regras de soma da QCD para calcular as massas e constantes de acoplamento ou decaimento dos estados exóticos theta+(1540) e cascata--(1862) (pentaquarks), dos mesons escalares charmosos DsJ+(2317), D0(2308) e D0(2405) e do meson axial X(3872). Os mesons foram também tratados como estados exóticos de quatro quarks (tetraquarks). Dois métodos de regra de soma foram aplicados e uma atenção especial foi dada aos limites de validade e incertezas da regra de soma. Em todos os casos encontramos resultados compatíveis com os dados experimentais existentes, mas no caso dos pentaquarks e dos mesons escalares as regras de soma têm algumas de suas condições violadas, levantando a questão sobre a existência das ressonâncias na forma em que foram propostas. Fizemos também uma previsão para um méson axial Xb, que é uma expansão para o setor botônico do modelo assumido para o X(3872). / In this work the QCD Sum Rules have been used to obtain masses and coupling or decay constants of the theta+(1540) and cascade--(1862) pentaquarks, the DsJ+(2317), D0(2308) and D0(2405) charmed scalar mesons and the X(3872) axial meson. The mesons have been treated as 4-quark exotic states (tetraquarks). Two sum rules methods have been used with special attention given to the limits and uncertainties of the sum rules. Results consistent with experimental data have been found in all cases, but some of the sum rules constraints have been violated in the calculation of the pentaquarks and scalar mesons, leaving questions about the existence of the states as they have been built here. A prediction was also made for the mass of a state expanding the model used for X(3872) to the botton sector, named Xb.

An important task of information retrieval is to induce classifiers capable of categorizing text documents. The fact that the same document can simultaneously belong to two or more categories is referred by the term multi-label classification (or categorization). Domains of this kind have been encountered in diverse fields even outside information retrieval. This dissertation discusses one challenging aspect of text categorization: the documents (i.e., training examples) are characterized by an extremely large number of features. As a result, many existing machine learning techniques are in such domains prohibitively expensive. This dissertation seeks to reduce these costs significantly. The proposed scheme consists of two steps. The first runs a so-called baseline induction algorithm (BIA) separately on different versions of the data, each time inducing a different subclassifier---more specifically, BIA is run always on the same training documents that are each time described by a different subset of the features. The second step then combines the subclassifiers by a fusion algorithm: when a document is to be classified, each subclassifier outputs a set of class labels accompanied by its confidence in these labels; these outputs are then combined into a single multi-label recommendation. The dissertation investigates a few alternative fusion techniques, including an original one, inspired by the Dempster-Shafer Theory. The main contribution is a mechanism for assigning the mass function to individual labels from subclassifiers. The system's behavior is illustrated on two real-world data sets. As indicated, in each of them the examples are described by thousands of features, and each example is labeled with a subset of classes. Experimental evidence indicates that the method can scale up well and achieves impressive computational savings in exchange for only a modest loss in the classification performance. The fusion method proposed is also shown to be more accurate than other more traditional fusion mechanisms. For a very large multi-label data set, the proposed mechanism not only speeds up the total induction time, but also facilitates the execution of the task on a small computer. The fact that subclassifiers can be constructed independently and more conveniently from small subsets of features provides an avenue for parallel processing that might offer further increase in computational efficiency.

This thesis describes the development of a new type of sensor for nitric oxide (NO) that can be used in a variety of combustion diagnostics and control applications. The sensor utilizes the absorption of ultraviolet (UV) radiation by the NO molecule to determine the concentration via optical absorption spectroscopy. UV radiation at 226.8 nm is generated by sum frequency mixing the outputs from a 395-nm external cavity diode laser (ECDL) and a 532-nm diode-pumped, intracavity frequency doubled Nd:YAG laser in a beta-barium borate (BBO) crystal. This radiation is used to probe the (v'=0, v"=0) band of the Α*Σ+ - Χ*π electronic transition of NO. The ECDL is tuned so that the UV radiation is in resonance with a specific energy level transition, and it is then scanned across the transition to produce a fully resolved absorption spectrum. Preliminary experiments were performed in a room-temperature gas cell in the laboratory to determine the accuracy of the sensor. Results from these experiments indicated excellent agreement between theoretical and experimental absorption line shapes as well as NO concentrations. Further experiments were performed at two actual combustion facilities to demonstrate the operation of the sensors in realistic combustion environments. Tests on a gas turbine auxiliary power unit (APU) at Honeywell Engines and Systems and on a well-stirred reactor (WSR) at Wright-Patterson Air Force Base produced excellent results despite the harsh temperatures and vibrations present. Overall, the sensitivity was estimated to be 0.8 parts per million (ppm) of NO (at 1000 K) for a 1 meter path length and the measurement uncertainty was estimated to be ±10%.

In general, subset sum problem is strongly believed to be computationally difficult to solve. But in 1983, Lagarias and Odlyzko proposed a probabilistic algorithm for solving subset sum problems of sufficiently low density in polynomial time. In 1991, Coster et. al. improved the Lagarias-Odlyzko algorithm and solved subset sum problems with higher density. Both algorithms reduce subset sum problem to finding shortest non-zero vectors in special lattices. In this thesis, we first proposed a new viewpoint to define the problems which can be solved by this two algorithms and shows the improved algorithm isn't always better than the Lagarias-Odlyzko algorithm. Then we verify this notion by experimentation. Finally, we find that the Lagrias-Odlyzko algorithm can solve the high-density subset sum problems if the weight of solution is higher than 0.7733n or lower than 0.2267n, even the density is close to 1.

Data warehouses contain data consolidated from several operational databases and provide the historical, and summarized data which is more appropriate for analysis than detail, individual records. On-Line Analytical Processing (OLAP) provides advanced analysis tools to extract information from data stored in a Data Warehouse. OLAP is designed to provide aggregate information that can be used to analyze the contents of databases and data warehouses. A range query applies an aggregation operation over all selected cells of an OLAP data cube where the selection is specified by providing ranges of values for numeric dimensions. Range sum queries are very useful in finding trends and in discovering relationships between attributes in the database. There is a method, prefix sum method, promises that any range sum query on a data cube can be answered in constant time by precomputing some auxiliary information. However, it is hampered by its update cost. For today's applications, interactive data analysis applications which provide current or "near current" information will require fast response time and have reasonable update time. Since the size of a data cube is exponential in the number of its dimensions, rebuilding the entire data cube can be very costly and is not realistic. To cope with this dynamic data cube problem, several strategies have been proposed. They all use specific data structures, which require extra storage cost, to response range sum query fast. For example, the double relative prefix sum method makes use of three components: a block prefix array, a relative overlay array and a relative prefix array to store auxiliary information. Although the double relative prefix sum method improves the update cost, it increases the query time. In the thesis, we present a method, called the recursive relative prefix sum method, which tries to provide a compromise between query and update cost. In the recursive relative prefix sum method with k levels, we use a relative prefix array and k relative overlay arrays. From our performance study, we show that the update cost of our method is always less than that of the prefix sum method. In most of cases, the update cost of our method is less than that of the relative prefix sum method. Moreover, in most of cases, the query cost of our method is less than that of the double relative prefix sum method. Compared with the dynamic data cube method, our method has lower storage cost and shorter query time. Consequently, our recursive relative prefix sum method has a reasonable response time for ad hoc range queries on the data cube, while at the same time, greatly reduces the update cost. In some applications, however, updating in some regions may happen more frequently than others. We also provide a solution, called the weighted relative prefix sum} method, for this situation. Therefore, this method can also provide a compromise between the range sum query cost and the update cost, when the update probabilities of different regions are considered.

A new cryptanalytic application is proposed for a number theoretic tool Weil sum to the birthday attack against multivariate quadratic trapdoor function. This new customization of the birthday attack is developed by evaluating the explicit Weil sum of the underlying univariate polynomial and the exact number of solutions of the associated bivariate equation. I designed and implemented new algorithms for computing Weil sum values so that I could explicitly identify some class of weak Dembowski- Ostrom polynomials and the equivalent forms in the multivariate quadratic trapdoor function. This customized attack, also regarded as an equation solving algorithm for the system of some special quadratic equations over finite fields, is fundamentally different from the Grobner basis methods. The theoretical observations and experiments show that the required computational complexity of the attack on these weak polynomial instances can be asymptotically less than the square root complexity of the common birthday attack by a factor as large as 2^(n/8) in terms of the extension degree n of F2n. I also suggest a few open problems that any MQ-based short signature scheme must explicitly take into account for the basic design principles.