Orientador: Luís Eduardo Evangelista de Araujo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-18T17:59:31Z (GMT). No. of bitstreams: 1 Carvalho_SilvaniaAlvesde_D.pdf: 4970692 bytes, checksum: f260af26ecacc7e92b1246968850ff9b (MD5) Previous issue date: 2011 / Resumo: Nesta tese apresentamos o estudo teórico de grades de difração induzidas em meios atômicos na condição de transparência induzida eletromagneticamente (EIT). As grades atômicas que serão descritas baseiam-se na não-linearidade Kerr gigante exibida pelos átomos sob EIT. No primeiro estudo realizado, a grade atômica é gerada a partir da modulação da não-linearidade Kerr através de uma onda estacionária. Neste estudo, aplicamos a teoria de ondas acopladas, desenvolvida originalmente para grades acústicas e holográficas, para a grade atômica de modo a obter uma expressão analítica para a eficiência de difração em primeira ordem. Altas eficiências de difração de um feixe de prova ressonante são previstas para incidência próxima ao ângulo de Bragg. Em um segundo estudo, descrevemos uma grade atômica do tipo ¿blazed¿ criada através da inserção de uma máscara de intensidade em um dos feixes responsáveis pela não-linearidade Kerr do meio. Eficiências de difração em primeira ordem para o feixe de prova próximas a 100% foram obtidas. Por último, discutimos uma grade de difração induzida na condição de coerência máxima entre os estados fundamentais de um átomo. Esta grade difrata não somente o feixe de prova incidente, mas também um segundo feixe gerado por mistura de quatro ondas. Apesar desta última grade apresentar eficiência de difração muito menor do que as duas grades anteriores, esta grade pode operar em vários comprimentos de onda diferentes, embora envolva sempre um feixe ressonante com alguma transição atômica. Além da contribuição teórica, trabalhos experimentais relacionados à área de aprisionamento e resfriamento de átomos foram realizados. Inicialmente, um experimento de espectrocopia de fotoassociação próximo ao limite de dissociação em uma amostra de 85Rb é apresentado. Em seguida, uma fonte de laser em 423 nm, formada por um laser de Ti-Sa com dobramento intracavidade através de um cristal LBO, que foi construída e estabilizada é descrita / Abstract: In this thesis we present a theoretical study on induced diffraction gratings in atomic media under electromagnetically induced transparency condition. The atomic gratings which will be described are based on the giant Kerr nonlinearity displayed by the atoms under EIT. In the first study, the atomic grating is generated from the modulation of the Kerr nonlinearity through a stationary wave. In this study, we apply coupled wave theory, originally developed for acoustic and holographic gratings, for an atomic grating in such a way that an analytical expression for the first order diffraction is obtained. High diffraction efficiencies of the resonant probe beam are predicted for incidence near Bragg angle. In a second study, we describe a blazed-type atomic grating created through the insertion of an intensity mask in one of the beam responsible for the Kerr nonlinearity of the medium. First order diffraction for the probe beam near 100% efficiency was observed. Finally, we discuss a diffraction grating induced under maximum coherence condition between the ground states of an atom. This grating diffracts not only the probe beam, but also a second beam generated by four wave mixing. Although this last grating shows a diffraction efficiency much smaller than the previous one, this grating can operate in several wavelengths, although involving a beam resonant with an atomic transition. Besides the theoretical contribution, experimental works related to the cooling and trapping of atoms were implemented. Initially, an experiment of photoassociation spectroscopy near the dissociation limit in a sample of cold rubidium atoms is presented. Following, a homebuilt laser source at 423 nm formed by a Ti-Sapphire laser with intracavity frequency doubling through a LBO crystal that was stabilized is described / Doutorado / Física Atômica e Molecular / Doutora em Ciências

The first confirmation of the presence of Colletotrichum gloeosporioides Penz. on cashew in Mozambique was based on a combination of observed symptoms, isolation and identification using basic morphological and molecular techniques. Anthracnose is now the second most important in the country, after powdery mildew caused by Oidium anacardii Noack. The present thesis represents a broad overview of the disease in Mozambique. The main focus of this study was thus to gather scientific information on the relevance of this disease in the country and through experimentation, generate recommendations that help farmers and decision makers to mitigate the disease pressure. The specific objectives of this study were as follows: - Provide a distinctive description of anthracnose symptoms on leaves through hostpathogen interaction studies in the laboratory. - Enhance current knowledge on the identity of Mozambican pathogen isolates, using DNA tools. - Assess the current anthracnose management practices, both at nursery and field level with a view to formulate timely, local and adequate management strategies. - Conduct experimental trials to select economically effective fungicides spraying programs for anthracnose disease management. ii - Search for variability and germplasm tolerance among dwarf and common cashew plant populations in Mozambique. By analyzing and integrating existing published literature on the subject, we successfully separated issues that concerned previously inaccessible information from those that reflect insufficient scientific knowledge. A survey was initiated to determine, the status of cashew anthracnose disease management practices in Mozambique. Subsequently, the information obtained was used to develop a national strategic framework for research and extension in the country. Areas identified as gaps were aligned with the main goals of this thesis and include: - Areas where scientific information lacked were identified. - The symptoms of the disease on leaves were successfully and distinctively distinguished from other common leaf diseases that simultaneously occur in orchards. - The pathogen isolates were identified using PCR techniques. The presence of Colletotrichum acutatum Simmonds was not confirmed at least not among the suspected and tested isolates. - Knowledge on the epidemiology of the disease was generated and its application for more effective disease management was successfully applied. - Effective fungicide applications and disease control programmes were developed for Colletotrichum gloeosporioides Penz.. - Appropriate nursery management strategies that reduce anthracnose disease development were developed. - Variability in germplasm reaction to the disease was demonstrated and therefore tolerant and susceptible genotypes were identified. - A technique for rapid and accurate evaluation of leaf anthracnose symptom grades was developed. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Microbiology and Plant Pathology / Unrestricted

The aim of this study was to explore teachers’ opinions and thoughts on teaching reading strategies to pupils in upper primary school in Sweden and how teachers explain their choices regarding texts and strategies. More specifically the aim was to highlight teachers’ perceptions and experience of teaching reading strategies. In this study semi-structured interviews were conducted with four teachers in grades 4-6 during the spring term of 2020. All four teachers taught Swedish as a school subject. The results of the study showed that the interviewed teachers each explain their choices of text according to their own set of criteria. When choosing reading strategies, the teachers based their choices largely on a particular course package developed in Sweden. The outlook the teachers had on the teaching of teaching reading strategies came across as positive. They felt that the strategies that they taught their pupils helped them to develop their reading comprehension skills. This was especially true for the low-achieving readers in the class. / Syftet med denna studie var att undersöka svensklärares uppfattningar och tankar om lässtrategiundervisning i årskurs 4–6 och hur de motiverar sina val av texter, strategiprogram och lässtrategier i den undervisningen. Mer specifikt har syftet varit att synliggöra lärares uppfattningar och erfarenheter om lässtrategiundervisning. Till studien har material samlats in genom metoden semistrukturerad intervju som är en kvalitativ metod. Intervjuerna genomfördes med fyra svensklärare i årskurs 4–6 under vårterminen 2020. Resultatet visar att lärarna motiverar sina val av texter med hjälp av flera kriterier och i deras val av lässtrategier utgick de från ett strategiprogram utvecklat i Sverige. Inställningen till lässtrategiundervisning framstod som positiv och lärarna upplevde den som främjande för elevernas läsförståelse, särskilt för de svaga läsarna.

Tal i bråkform är en viktig del av den svenska läroplanen, ett räknesätt som många elever har svårt att förstå. Lärare behöver vara insatta i olika undervisningsmetoder för tal i bråk-form, för att skapa bra undervisningstillfällen för elever. Detta behövs speciellt för elever i matematiksvårigheter. Undervisning ska anpassas utifrån elevers behov, vilket sker bäst när lärare känner till undervisningsmetoder som är fördelaktiga för elevers inlärning. Denna litte-raturstudie presenterar därför 15 undervisningsmetoder som forskning konstaterar som fördel-aktiga för undervisning om tal i bråkform för elever i matematiksvårigheter. Undervisnings-metoderna skiljer sig åt och är fördelaktiga på olika sätt. Undervisningsmetoderna passar också olika bra beroende på elevers tidigare kunskaper. Samtliga undervisningsmetoder för-klaras för att ge en tydlig bild av hur de kan bidra till fördelaktiga inlärningstillfällen för ele-ver i matematiksvårigheter. / Fractions is an important part of the Swedish curriculum, which many students have diffi-culties understanding. Teachers need to be familiar with different teaching methods for frac-tions to create good teaching opportunities for students. Especially for students with mathe-matic difficulties. Teaching should be adapted based on students’ needs, which happens best when teachers know which teaching methods that are beneficial for students’ learning. This literature study therefore presents 15 teaching methods that research finds to be advantageous for teaching fractions to students in mathematical difficulties. The teaching methods differ and are advantageous in different ways. The teaching methods also suit the students differ-ently depending on the students’ previous knowledge. All 15 teaching methods are explained to give a clear picture of how they can contribute to advantageous learning opportunities for students with mathematical difficulties.

It has been reported in the media that teachers can be influenced by other factors than students'knowledge when grading, something that the grades should reflect. Previous studies have also shownthat grades can be affected by other factors than students' knowledge, however, there are no studiesthat have shed light on how social studies teachers experience the grading practice, a research gapthat we intended to fill. The subject of social studies has a significant role to play in socializingcitizens in society. If teachers set grades that do not reflect students' knowledge, it is conceivable thatstudents will have different perceptions of their knowledge, which may affect their future. Thepurpose of this work was to investigate whether teachers of social studies in upper secondary schoolexperience that they can give fair grades to their students. By the method grounded theory, we havethrough semi-structured interviews with four teachers developed theoretical concepts based on theirexperiences. The result of our analysis indicated that the teachers experience that the grades are basedon students' knowledge. On the other hand, the analysis also showed that the grading can beinfluenced by external actors and expectations, students 'characteristics, resources at the school anduncertainty about students' knowledge. / <p>21-01-20</p>

This study aims to give an overview of school segregation in Stockholm and its development during the period 2000 to 2010. Further, it aims to examine the effects of school segregation on student achievement. The first part of the study uses register data to measure segregation in schools from 2000 to 2010, the second part utilizes the Stockholm School Survey 2010 for measuring student demographics and school achievement. The examination of school segregation in Stockholm reveal a substantial segregation between schools, on both levels of non-native background and parental education. The trends have been stable for segregation on non-native background and decreased slightly for parental education from 2000 to 2010, however, they both remain at relatively high levels. Multilevel analysis show that student school achievement is negatively impacted by increased concentration of students with disadvantaged characteristics, i.e. higher levels of students with non-native background and lower levels of parental education. The results also indicate that non-native students are more negatively affected by these effects. Further, the analysis tests for threshold effects of segregation, but no such effects can be identified and it seems to be more or less linear, higher degree of segregation leads to stronger effects. It is concluded that differences between schools have an unequal and unfair effect on student school achievement.

Syftet med studien var att öka kunskapen om hur grundlärare i årskurs 4–6 resonerar om valet av skönlitteratur i sin undervisning och vad dessa val grundar sig på. Frågeställningarna i studien är följande:  ·       Hur beskriver lärarna skönlitteraturens betydelse och funktion i sin undervisning?  ·       Vilka faktorer tar lärarna hänsyn till i sina val av skönlitterära böcker?  Som metod för att besvara studiens syfte har kvalitativa semistrukturerade intervjuer använts. Intervjuerna har genomförts med fyra grundlärare från tre olika län som har ett särskilt intresse för skönlitteraturen i sin undervisning.  I resultatet framgår att det som påverkar lärarnas litteraturval allra mest är deras elever. Dock upplever lärarna att det kan vara svårt att hitta skönlitteratur som passar alla elever och poängterar därför vikten av att ha tillgång till en variation av skönlitterära böcker. En annan aspekt som lärarna uppmärksammade som betydelsefull var att själva vara pålästa om boken för att kunna diskutera innehållet och svara på elevernas frågor. För tankar skall aldrig lämnas åt sitt öde menade lärarna. / The aim of this study was to increase the understanding of the selection process used by elementary school teachers for literary fiction and their reasoning behind it. The following questions are included in this study: ·       How do teachers describe the meaning and function of literature in their teaching? ·       What factors do teachers consider in their choice of fiction?  Semi-structured interviews have been used as a research method. The interviews were conducted with four elementary school teachers from three different schooling districts in Sweden. The teachers selected were responsible for choosing the literary fiction.   The results show that the teacher’s choices are made for the benefit of the students. However, teachers experienced difficulties finding literature that suits every student. It is important that the reading selection is varied. Another important aspect that was highlighted during this study was that teachers themselves are knowledgeable and well-read on the subject. This enhances their ability to answer student’s questions and to further academical discussions. Like the teachers said, thoughts should never be left to their fate.

Studiens syfte är att undersöka lärares uppfattningar om läs- och skrivsvårigheter hos elever på mellanstadiet och hur mellanstadielärare uppger att de arbetar med dessa elever. Det teoretiska ramverk som ligger till grund för studien är kognitiva processer och läsningens fem utvecklingsdimensioner. Sju kvalitativa semistrukturerade intervjuer utförs för att samla in data. Resultatet visar att mellanstadieelevers svårigheter är läsförståelse, fonologisk medvetenhet, avkodning, stavning och grammatik. När lärare upptäcker läs- och skrivsvårigheter tar de direktkontakt med elever, anpassar materialet efter elevers behov, tar kontakt med speciallärare eller specialpedagog och kontaktar vårdnadshavare. Resultatet visar även att mellanstadielärare använder sig av grupp- och pararbeten, en-till-en undervisning, motivationsskapande undervisning, undervisning som är fokuserad på språk- och läsförståelse och digitala verktyg. Elever i läs- och skrivsvårigheter behöver varierad undervisning och olika arbetsmetoder för att utveckla deras läs- och skrivförmågor. Om eleverna tidigt och utifrån sina egna behov får hjälp, stöttning och anpassningar kan det hjälpa dem att komma ur dessa svårigheter.

School is supposed to be a place of equal opportunity for all students to achieve academic success no matter who they are or what background they have. Yet in the Swedish school today, girls generally perform better and receive better grades than boys regardless of socioeconomic background or ethnicity. This trend is not exclusive to Sweden; multiple countries experience this as well as reported by OECD (2020). The purpose of this project is to study why girls outperform boys in the Swedish school. This project applies the hypothesis that girls are, consciously or unconsciously, more encouraged and have higher expectations placed upon them by their teachers, guardians and their classmates. To study this a survey was handed out to 75 students of both sexes where they answered questions about their academic achievements as well as about their general, inner and outer motivation, encouragement and expectations from their teachers, guardians and classmates. The results show that the students have the same general motivation and experience almost equal encouragement from teachers and guardians. Girls, however, have slightly higher inner motivation, much higher outer motivation and experience much more encouragement from their classmates as well as higher expectations from their teachers, guardians and their classmates than boys do. These results are then analyzed and compared to what previous research found and eventual differences are discussed.

Throughout our teacher training program, we have noticed that students struggle to see the reason with writing task designs that are short and concludes upon the end of the lesson. Therefore, this degree project aims to gain an insight to whether the methods used in process writing and its various concepts can be used efficiently within schools to assist students in reaching higher grades and have higher rates of academic success, as well as discover the impacts of motivation tied in with the use of these specific task designs. This paper will firstly introduce an overview of the different theories and concepts that are tied to process writing, such as feedback, rubrics use. In prior studies made, researchers have found that academic success is influenced by the use of strategies that correlate to the methods in process writing, and also describes how this impact is made. Secondly, this degree project is based on interviews made with three active 7-9 English teachers and 15 students (in years 8-9) in the southern of Sweden to research the possibility of motivation being affected in any way through the use of these task designs that, according to researchers, will lead the students to higher rates of academic success. The major conclusions of this study are that (I) students and teachers feel that it is useful to utilize the different key concepts tied to process writing in order to gain proficiency in the English language, (II) teachers often use at least one, if not more, of the methods included in process writing, and feel that they have an impact on student learning within the subject, (III) students feel that their motivation can be impacted through the use of these strategies, and be affected differently based on teacher instruction, (IV) many of the schools that were visited have grade-oriented students that can affect student motivation to learn, and the reasons for learning, (V) in addition to how well the students feel engaged to work with a task depending on their interests. (VI) Lastly, it also has an impact at what stage the teacher decides to assess their students, while working with process writing tasks.