Analysis of the cognitive unity or rupture between conjecture and proof when learning to prove on a grade 10 trigonometry course

We present results from a classroom-based intervention designed to help a class of grade 10 students (14–15 years old) learn proof while studying trigonometry in a dynamic geometry software environment. We analysed some students’ solutions to conjecture-and-proof problems that let them gain experience in stating conjectures and developing proofs. Grounded on a conception of proof that includes both empirical and deductive mathematical argumentations, we show the trajectories of some students progressing from developing basic empirical proofs towards developing deductive proofs and understanding the role of conjectures and proofs in mathematics. Our analysis of students’ solutions is based on networking Boero et al.’s construct of cognitive unity of theorems, Pedemonte’s structural and referential analysis of conjectures and proofs, and Balacheff and Margolinas’ cK¢ model, while using Toulmin schemes to represent students’ productions. This combination has allowed us to identify several emerging types of cognitive unity/rupture, corresponding to different ways of solving conjecture-and-proof problems. We also show that some types of cognitive unity/rupture seem to induce students to produce deductive proofs, whereas other types seem to induce them to produce empirical proofs.     

Continuous frequency and phase spectrograms： a study of their 2D and 3D capabilities and application to musical signal analysis

A new lighting and enlargement on phase spectrogram （PS） and frequency spectrogram （FS） is presented in this paper. These representations result from the coupling of power spectrogram and short time Fourier transform （STFT）. The main contribution is the construction of the 3D phase spectrogram （3DPS） and the 3D frequency spectrogram （3DFS）. These new tools allow such specific test signals as small slope linear chirp, phase jump case of musical signal analysis is reported. The main objective is to and small frequency jump to be analyzed. An application detect small frequency and phase variations in order to characterize each type of sound attack without losing the amplitude information given by power spectrogram     

Persecution and behavior: a report of refugee children from Chile

A Swedish study of 50 newly resettled refugee children from Chile describes the children's experiences of persecution in their home country and coping patterns in the receiving country. Thirty-six children had experiences directly related to persecution, and seven of these had been victims of physical assault for political reasons. Sleep disturbances and dependency were behaviors significantly associated with experiences of persecution. Resettled refugee families need to be approached by concerned professionals as symptoms of trauma in refugee children are often recognized only in the family sphere.     

Women mentoring in the academe: a faculty cross-racial and cross-cultural experience

Two women faculty members, one White from the southeastern United States and one Black African from Zimbabwe, purposefully explored their informal mentoring relationship with the goal of illuminating the complexities associated with their cross-racial, cross-cultural experience. Concentrating on their four-year mentor-mentee academic relationship at a predominantly White institution (PWI), these women employed a dialogic duoethnographic methodology to uncover emerging, nuanced characteristics contributing to the positive nature of their mentoring experience. Calling upon a seminal nine-function mentoring framework focused on advancing mentee personal growth and professional advancement, the authors, engaged in critical interplay of dialogic considerations of their mentoring experiences, relationship, and literature. The authors revealed a distinct cross-cultural and cross-racial journey where each, as participant researcher, uncovered a deeper appreciation for the importance of engaged dialog. Emerging is a complex interplay of understandings about trust, care, and power dynamics as factors in defining mentoring relationships that work for good.     

Implicit indexing of natural language text by reorganizing bytecodes

Word-based byte-oriented compression has succeeded on large natural language text databases, by providing competitive compression ratios, fast random access, and direct sequential searching. We show that by just rearranging the target symbols of the compressed text into a tree-shaped structure, and using negligible additional space, we obtain a new implicitly indexed representation of the compressed text, where search times are drastically improved. The occurrences of a word can be listed directly, without any text scanning, and in general any inverted-index-like capability, such as efficient phrase searches, can be emulated without storing any inverted list information. We experimentally show that our proposal performs not only much more efficiently than sequential searches over compressed text, but also than explicit inverted indexes and other types of indexes, when using little extra space. Our representation is especially successful when searching for single words and short phrases.     

The type,amount, frequency and timing of dietary supplement use by elite players in the First Spanish Basketball League

The aims of this study were to determine the type, frequency and amount of dietary supplement consumption among a group of professional basketball players. The type, amount and specific timing of supplement use were recorded by 55 professional basketball players from seven different teams of the First Spanish Basketball League. Most participants (58%) consumed dietary supplements. Multivitamins and vitamins were the most frequently used supplements among the athletes (50.9%), followed by sport drinks (21.8%), miscellaneous supplements (21.8%), amino acids (14.5%), proteins (12.7%) and carbohydrates (12.7%). The average daily dietary supplement was one capsule of multivitamins, one capsule of antioxidant vitamins, 0.2-1.0 g vitamin C, 10.3 g protein, 1.9 g amino acids, 16.2 g carbohydrates and 377 ml of a commercial sport drink. Although the proportion of participants who consumed dietary supplements before, during and immediately after exercise was 25.4%, 16.3% and 7.3% respectively, only a few consumed a potentially ergogenic supplement at these times. It would appear unlikely that the type or amount of dietary supplements consumed had a beneficial effect on the physical performance of these professional basketball players, with the possible exception of antioxidant vitamins and the commercial sport drinks.     

Intermittent hypoxia exposure in a hypobaric chamber and erythropoietin abuse interpretation

Abstract

The aim of this study was to assess the effect of intermittent hypoxia exposure on direct and indirect methods used to evaluate recombinant human erythropoietin (rhEPO) misuse. Sixteen male triathletes were randomly assigned to either the intermittent hypoxia exposure group (experimental group) or the control normoxic group (control group). The members of the experimental group were exposed to simulated altitude (from 4000 to 5500 m) in a hypobaric chamber for 3 h per day, 5 days a week, for 4 weeks. Blood and urine samples were collected before and after the first and the final exposures, and again 2 weeks after the final exposure. While serum EPO significantly increased after the first [from a mean 8.3 IU · l^?1 (s = 3.2) to 16.6 IU · l^?1 (s = 4.7)] and final exposures [from 4.6 IU · l^?1 (s = 1.4) to 24.8 IU · l^?1 (s = 9.3)], haemoglobin, percentage of reticulocytes, and soluble transferrin receptor were not elevated. Second-generation ON/OFF models (indirect rhEPO misuse detection) were insensitive to intermittent hypoxia exposure. The distribution of the urinary EPO isoelectric profiles (direct rhEPO misuse detection) was altered after intermittent hypoxia exposure with a slight shift towards more basic isoforms. However, those shifts never resulted in misinterpretation of results. The intermittent hypoxia exposure protocol studied did not produce any false-positive result for indirect or direct detection of rhEPO misuse in spite of the changes in EPO serum concentrations and urinary EPO isoelectric profiles, respectively.     

Valoración diagnóstica de la Batería Piaget-Head (Primera parte)

RESUMEN

Se presenta una discusión crítica sobre el uso de la batería de Piaget-Head para la valoración diagnóstica de dificultades en el aprendizaje. Esta batería fue elaborada por Galifret-Granjon a partir de la selección de pruebas provenientes de Piaget y Head. El estudio encuentra errores en la elaboración de la batería. Los objetivos de las pruebas de Piaget discrepan de los objetivos originales del autor y las pruebas procedentes de Head se escogen según un criterio inadecuado. Los errores que se puedan cometer en la batería parecen más bien debidos a la forma operativa (adecuada o inadecuada) con que el sujeto elabora, que a una alteración del esquema corporal, de la orientación espacial, o de la estructuración del lenguaje.