916 research outputs found
Studentsâ Evolving Meaning About Tangent Line with the Mediation of a Dynamic Geometry Environment and an Instructional Example Space
In this paper I report a lengthy episode from a teaching experiment in which fifteen Year 12 Greek students negotiated their
definitions of tangent line to a function graph. The experiment was designed for the purpose of introducing students to the
notion of derivative and to the general case of tangent to a function graph. Its design was based on previous research results on
studentsâ perspectives on tangency, especially in their transition from Geometry to Analysis. In this experiment an instructional
example space of functions was used in an electronic environment utilising Dynamic Geometry software with Function
Grapher tools. Following the Vygotskian approach according to which studentsâ knowledge develops in specific social and
cultural contexts, studentsâ construction of the meaning of tangent line was observed in the classroom throughout the
experiment. The analysis of the classroom data collected during the experiment focused on the evolution of studentsâ personal
meanings about tangent line of function graph in relation to: the electronic environment; the pre-prepared as well as
spontaneous examples; studentsâ engagement in classroom discussion; and, the role of researcher as a teacher. The analysis
indicated that the evolution of studentsâ meanings towards a more sophisticated understanding of tangency was not linear. Also
it was interrelated with the evolution of the meaning they had about the inscriptions in the electronic environment; the
instructional example space; the classroom discussion; and, the role of the teacher
Reducing the oral quinine-quinidine-cinchonin (Quinimax) treatment of uncomplicated malaria to three days does not increase the recurrence of attacks among children living in a highly endemic area of Senegal
A 3 d shortened course of the quinine-quinidine-cinchonin association Quinimax (trademark) was compared to the usual 7 d regimen for routinely treating 462 acute uncomplicated #Plasmodium falciparum and the partial acquired immunity of the children were probably responsible for the absence of any difference between the courses. Oral Quinimax (trademark) for 3 d is a possible alternative regimen to chloroquine and sulfadoxine-pyrimethamine for treating uncomplicated malaria in highly endemic areas of Africa where clinical resistance to these drugs exists. (Résumé d'auteur
Diagnosing students' difficulties in learning mathematics
This study considers the results of a diagnostic test of student difficulty and contrasts the difference in performance between the lower attaining quartile and the higher quartile. It illustrates a difference in qualitative thinking between those who succeed and those who fail in mathematics, illustrating a theory that those who fail are performing a more difficult type of mathematics (coordinating procedures) than those who succeed (manipulating concepts). Students who have to coordinate or reverse processes in time will encounter far greater difficulty than those who can manipulate symbols in a flexible way. The consequences of such a dichotomy and implications for remediation are then considered
A Friendly Introduction to "Knowledge in Pieces": Modeling Types of Knowledge and Their Roles in Learning
The Evolution of Technology and the Mathematics of Change and Variation: Using Human Perceptions and Emotions to Make Sense of Powerful Ideas
The fundamental cycle of concept construction underlying various theoretical frameworks
In this paper, the development of mathematical concepts over time is considered. Particular reference is given to the shifting of attention from step-by-step procedures that are performed in time, to symbolism that can be manipulated as mental entities on paper and in the mind. The development is analysed using different theoretical perspectives, including the SOLO model and various theories of concept construction to reveal a fundamental cycle underlying the building of concepts that features widely in different ways of thinking that occurs throughout mathematical learning
Complications des otites moyennes chroniques
Objectif de lâĂ©tude : Rapporter la frĂ©quence des complications des otites moyennes chroniques et prĂ©senter notre expĂ©rience dans leur prise en charge.MatĂ©riel et mĂ©thodes : Etude rĂ©trospective concernant la pĂ©riode allant du 1er janvier 2000 au 31 dĂ©cembre 2009. Les complications ont Ă©tĂ© rĂ©parties en 2 grands groupes : extracrĂąniennes et intracrĂą-niennes.RĂ©sultats : 57 patients sur 350 reçus pour OMC ont prĂ©sentĂ© une complication, soit une frĂ©quence de 18,38 %. Le cholestĂ©atome était le plus grand pourvoyeur de ces complications (84,2%). Dix-neuf patients prĂ©sentaient plus dâune complication, soit au total 76 cas. Les complications extracrĂąniennes ont Ă©tĂ© les plus frĂ©quentes, 63 cas (83%), dominĂ©es par la mastoĂŻdite extĂ©riorisĂ©e profuse (68,3%). Les complications intracrĂąniennes au nombre de 13 (17%) Ă©taient dominĂ©es par la mĂ©ningite purulente otogĂšne (46,2%). La mastoĂŻdectomie associĂ©e Ă une antibiothĂ©rapie Ă large spectre, occupait une place im-portante dans la prise en charge de ces complications. Elle a Ă©tĂ© rĂ©alisĂ©e chez 45 patients (79%). La mortalitĂ© a Ă©tĂ© estimĂ©e Ă 3,5% (2 cas de dĂ©cĂšs). Un drainage neurochirurgical a Ă©tĂ© effectuĂ© dans 4 cas (8,6 %).Conclusion : Cette Ă©tude se caractĂ©rise par un taux de complications dâOMC plus Ă©levĂ© que ceux rappor-tĂ©s dans la littĂ©rature, ainsi que par la prĂ©dominance des formes Ă©tendues et des associa-tions de complications chez un mĂȘme patient.Mots clĂ©s : Otite moyenne chronique, Complications, CholestĂ©atome.The objective of this study : was to report the frequency and our experience of management of complications of chronic otitsmedia.Methods : We conducted a retrospective study covering 10 years period (from 1st January 2000 to 31 December 2009). Complications were divided into 2 groups: extracranial and intracranial.Results : Among 350 patients received for chronic otitis media, 57 presented complications, such as a rate of 18.38%. Cholesteatoma was the largest provider of these complications in order of 84.2%. Nineteen (19) patients had more than one complication. So, a total of 76 cases of complications were listed. Subperiostal mastoiditis was the most common findings, 68.3% of the extracranial complications. The intracranial complications, (17%), were domi-nated by otogenic purulent meningitis (46.2%). Radical mastoĂŻdectomy with broad spectrum antibiotics occupied an important place in the management of these complications, performed in 45 patients (79%). Neurosurgical drainage was performed in 4 cases (8.6%). Mortality was estimated at 3.5% (2 deaths).Conclusion : COCM are characterized, in this study, by an elevated rate compared to that reported in the literature, the prevalence of extended forms and associations of complications in the same patient.Keys words : Chronic otitis media, Complications, Cholesteatoma
Myringoplastie par la technique des boutonniĂšres
Introduction : La rĂ©paration des lĂ©sions tympaniques et ossiculaires au cours de lâotite chronique fait appel Ă plusieurs procĂ©dĂ©s bien codifiĂ©s par leurs utilisateurs.Le but de ce travail est de rapporter nos rĂ©sultatsde myringoplastie par la technique des boutonniĂšres, chez des patients porteurs de sĂ©quelles dâotite moyenne chronique non cholestĂ©atomateuse.Patients et mĂ©thode : Etude rĂ©trospective concernant 49 patients opĂ©rĂ©s consĂ©cutivement de tympanoplastie pour otite moyenne chronique non cholestĂ©atomateuse, entre janvier 2003 et dĂ©cembre 2009, sĂ©lectionnĂ©s parmi 140 autres opĂ©rĂ©s de tympanoplasties selon dâautres procĂ©dĂ©s. Le temps de rĂ©paration de la membrane tympanique (Myringoplastie) a étĂ© effectuĂ© par la technique dâamarrage antĂ©rieur du greffon, technique dite des boutonniĂšres. Les critĂšres dâĂ©valuationĂ©taient lâĂ©tat du tympan Ă la derniĂšre consultation, le rinne moyen post opĂ©ratoire ou rinne rĂ©siduel et le gain moyen auditif. Le gain auditif Ă©tait reprĂ©sentĂ© par la diffĂ©rence entre le rinne prĂ©-opĂ©ratoire et le rinne post opĂ©ratoire et tous les paramĂštres fonctionnels apprĂ©ciĂ©s sur les frĂ©quences 500, 1000 et 2000 hertz.RĂ©sultats : LâĂąge moyen Ă©tait de 29 ans avec des extrĂȘmes de 8 et 64 ans. La perforation tympanique Ă©tait importante, centrale ou subtotale dans 32 cas (65,30%), avec une anciennetĂ© remontant Ă lâenfance dans 19 cas (38,77%). Lâoreille controlatĂ©rale Ă©tait porteuse dâune pathologie dans 23 cas (47%). Le rinne moyen prĂ©-opĂ©ratoire Ă©tait de 37,04 dB. Avec un recul moyen de 26 mois, la restauration anatomique du tympan en position normale Ă©tait notĂ©e dans 35 cas (71,42 %). Le taux de reperforation a Ă©tĂ© estimĂ© Ă 20,4% (10 cas), tandisque la mĂ©dialisation a Ă©tĂ© observĂ©e dans 2 cas (4,08%), la latĂ©ralisation dans 1 cas (2,04%), le blunting ou comblement de lâangle antĂ©rieur tympano-mĂ©atal dans 1 cas (2,04%). Nous avons notĂ© un rinne moyen post opĂ©ratoire de 20,38 dB avec un gain moyen post opĂ©ratoire de 14dB.Conclusion : Les rĂ©sultats obtenus dans cette premiĂšre sĂ©rie de myringoplastiepar la technique des boutonniĂšres ont étĂ© modestes, mais amĂ©liorĂ©s dans le temps avec la maitrise de la technique opĂ©ratoire et des facteurs de risque dâĂ©chec reprĂ©sentĂ©s ici par lâanciennetĂ©, lâimportance et lâĂ©volutivitĂ© des lĂ©sions.Mots clĂ©s : Otite chronique, Myringoplastie, Technique des boutonniĂšres.Objective : Several methods well codified by their users had been described for the repairing of tympanic and ossicular damage during chronic otitis media. The aim of this study was to report our results of myringoplasties by the technic of buttonholes procedure, in patients with sequelae of non chlesteatoma chronic otitis media.Patients and methods : A retrospective study on 49 patients, with sequalea of non cholesteatoma chronic otitis media, operated consecutively of myringoplasty by the technic of buttonholes, between january 2003 and december 2009, was caried out. The patients had been selected among 140 others operated throught others procedures. The criteria of evaluation were the ear drumâs aspect at the last clinical examination, the average air bone gap and the average hearing gain established as the difference between pre opĂ©rative and post operative air bone gap. The parameters for the post operative functional outcome had been assessed on the frequencies 500, 1000 and 2000 kHz.Results: The average age was 29 years and ranged from 8 to 64. The tympanic membraneâs perforation was important, central or subtotal in 32 cases (65,30%), with a long term Ă©volution dating back to childhood in 19 cases (38,77%). Pathological disease was noticed in the controlateral ear in 23 cases (47%). The average pre operative air bone gap was 37.04 dB. After a mean follow up of 26 month, the succeful rate of closure of the tymapanic membrane, in the normal position, was 71,42%. The recidive of perforation (reperforation) was estimated at 20,4% (10 cases), whereverthe medialization was observed in 2 cases (4,08), lateralization and the blunting or filling the anterior tympano-mĂ©atal angle in respectively 1 case (2,04%). We noted an average post oprative air bone gap of 20,38 dB with an average hearing gain of 14 dB.Conclusion: The results obtained in this first round of myringoplasty with buttonhole procedure were modest, but improved over time withthe mastery of the surgery technic and risks factors of failure represented here by the age, size and scalabillity of the lesions.Keyswords : Chronic otitis media, Myringoplasty, Technic of buttonhole
Osteolipoma: An unusual tumor of the parotid region
SummaryPurpose of studyOncology of the parotid region is rich and varied, like its components. During his career, the ENT surgeon may come across such an exceptional tumor as osteolipoma. The aim of this study was to describe the rarity and the etiopathogeny of osteolipoma with parapharyngeal location.Patients and methodWe had the opportunity to find this uncommon tumor in a 21-year-old female patient. The mass located in the parotid region was hard, barely mobile and at first looked like a parotid tumor. Total parotidectomy with facial nerve preservation was performed. It revealed a stony and dented tumor inside the internal lobe of the parotid located in the parapharyngeal space between the vertical portion of the mandible anteriorly and the styloid apophyse posteriorly. Macroscopic examination of the piece evidenced a lipomatous mass with hard as bone nodes in its middle. Histology revealed an osteolipoma.ConclusionA review of the literature shows the uncommon occurrence of this type of tumor. A few rare cases were reported among which two involving the parapharyngeal space
Stevin numbers and reality
We explore the potential of Simon Stevin's numbers, obscured by shifting
foundational biases and by 19th century developments in the arithmetisation of
analysis.Comment: 22 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1104.0375, arXiv:1108.2885, arXiv:1108.420
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