What do students do in self-formed mathematics study groups?

An implicit assumption of many university classes is that students will spend a large amount of time outside the classroom refining their understanding of the material to develop mastery of the concepts. This is especially true in first year mathematics courses at the undergraduate level. However, little is known about what students do to fulfill this didactical contract with their instructors. The currently available research relies primarily on self-reported data from the students collected through questionnaires or interviews. This study sought to start describing what students do while studying mathematics in a self-created group outside of the classroom setting through direct observation. In particular, this study provides a mathematical foundation for determining study groups, identifies what materials students utilize while studying together, develops a method for describing the activities that occur over the course of a study session through the use of macrotasks and microtasks, and identifies what roles students enacted during group problem solving sessions

Ethnically Biased? Experimental Evidence from Kenya

Ethnicity has been shown to shape political, social, and economic behavior in Africa, but the underlying mechanisms remain contested. We utilize lab experiments to isolate one mechanism - an individual's bias in favor of coethnics and against non-coethnics - that has been central in both theory and in the conventional wisdom about the impact of ethnicity. We employ an unusually rich research design involving a large sample of 1300 participants from Nairobi, Kenya; the collection of multiple rounds of experimental data with varying proximity to national elections; within-lab priming conditions; both standard and novel experimental measures of coethnic bias; and an implicit association test (IAT). We find very little evidence of an ethnic bias in the behavioral games, which runs against the common presumption of extensive coethnic bias among ordinary Africans and suggests that mechanisms other than a coethnic bias in preferences must account for the associations we see in the region between ethnicity and political, social, and economic outcomes

Motivasi Dan Karakteristik Sosial Ekonomi Rumah Tangga Penanam Pohon Penghasil Kayu Pertukangan : Kasus Tradisi Menanam Kayu Bawang (Disoxylum Molliscimum Bl) Oleh Masyarakat Kabupaten Bengkulu Utara, Bengkulu

Secara umum pelaksanaan Pembangunan kehutanan selama dekade terakhir didasarkan pada komoditi kayu, dan informasi yang diketahui tentang bagaimana masyarakat dapat menerima jenis-jenis tersebut untuk ditanam secara tradisional sangat sedikit. Pengetahuan tentang motivasi dan ciri-ciri rumah tangga terhadap pertumbuhan jenis tradisional tersebut penting dalam pengembangannya dan penyempurnaan dalam pelaksanaannya. Tulisan ini bertujuan untuk mengetahui hubungan motivasi dengan karakteristik rumah tangga petani kayu bawang di kabupaten Bengkulu Utara, Provinsi Bengkulu. Analisa data menggunakan metode chi-square untuk melihat hubungan antara karakteristik rumah tangga dengan tingkat motivasi penanaman pohon. Hasil analisis menunjukkan bahwa masyarakat Kabupaten Bengkulu Utara mempunyai motivasi sedang sampai tinggi untuk menanam pohon; yang didorong oleh faktor ekonomi seperti kebutuhan konsumsi dan untuk persediaan kayu untuk kebutuhan di masa mendatang, perasaan puas terhadap USAha perkayuan sekarang dan keinginan untuk mempertahankan pohon, ii) motivasi yang tinggi untuk menanam pohon berhubungan dengan ukuran luas lahan petani; petani yang mempunyai lahan yang luas akan mendukung tanaman campuran dan tingkat pendidikan yang rendah dari kepala rumah tangga petani akan mempengaruhi kekonsistenan dalam pelaksanaan kegiatan. Berdasarkan hasil penelitian ini pembelajaran antar petani perlu dipertimbangkan sebagai USAha penyuluhan dalam pengembangan tanaman kayu

Bioaccumulation d'aluminium chez la truite Salmo truffa fario soumise au retombées des pluies acides : étude structurale, ultrastructurale et microanalytique

Des études microanalytiques ont été menées sur des truites Salmo trutta fario, âgées de deux ans, récoltées dans une rivière des Vosges soumise aux retombées des pluies acides et sur des truites témoins récoltées dans une rivière d'Auvergne, non soumise aux pluies acides. La rivière des Vosges est caractérisée par un pH de 5,42 et par une concentration en aluminium de 200 µg/L-1. Notre but étant de déterminer les tissus, cellules et organites cibles de bioaccumulation éventuelle de l'aluminium, nous avons analysé rein, foie, branchie et tractus digestif. Deux méthodes microanalytiques ont été utilisées pour localiser l'aluminium à l'échelle cellulaire et subcellulaire et connaître les éléments avec lesquels il peut être associé; ce sont la spectrométrie de masse par émission ionique secondaire (microscope ionique associé à un système informatisé de traitement d'images) et la spectrométrie des rayons X (microsonde électronique de Castaing associée à un microscope électronique à transmission).La microanalyse des rein, foie, branchie et tractus digestif montre l'existence de deux processus conduisant à la bioaccumulation de l'aluminium. Le premier, classiquement connu pour d'autres métaux, met en évidence une insolubilisation de l'aluminium sous forme de phosphate, dans des organites limités par une membrane : les lysosomes et les granules pigmentaires des mélanocytes. Le second, démontre la formation de volumineux dépots extra-cellulaires, atteignant 100 µm de long et entraînant la destruction du tissu. Aucune bioaccumulation significative d'aluminium n'a été observée chez des truites témoins, récoltées dans le centre de la France, où l'eau à pH 7.9 est dépourvue d'aluminium.The major harm caused by acidic precipitation is shown by a disappearance of fish. Other factors besides acidity such as aluminium levels are significantly harmful and many studies have shown that aluminium ions are toxic to fish. The only sensible course of action is to investigate the basic mechanisms by which each of the metal pollutants enters and attacks living systems. For this, one needs to be a combination of physicist, chemist, biochemist, physiologist and toxicologist. Investigations on metal bioaccumulation require very sensitive analytical instrumentation. Total analytical methods commonly used are inadequate : absorbed and adsorbed elements cannot be distinguished.Therefore, interesting information can be obtained by using physical methods of chemical microanalysis : two available microanalytical techniques are particularly suitable, X-ray spectrometry and secondary ion mass spectrometry.X-ray spectrometry, also called Electron Probe X-ray Microanalysis or Electron Microprobe (EMP) provides a means for studying the local chemical composition and structure of biological specimens. EMP can be used in association with a photon microscope or with a transmission electron microscope allowing the detection of elements at subcellular level.The Secondary Ion Mass Spectrometry (SIMS), also called Ion Microscopy, allows to visualize, analyse and photograph the microscopical distribution of the stable or radioactive isotopes of the elements present in a histological section. The sensitivity of the method is very high, ranging from 0.1 to 1 ppm. In association with SIMS, a processing of secondary ion images is used.Two years-old samples of Salmo trutta fario, from wild populations living in acidified waters of Eastern France (near Cornimont in the Vosges moutains) were studied for aluminium detection at cellular and subcellular levels. The acidified waters were characterized by a low pH (5,42) and high aluminium level reaching 200 µg/L-1. Control trouts living in non acidified waters (pH : 7.9 and aluminium free) of central France (near Clermont-Ferrand) were used for comparison. In order top determine the tissues, cells and organelles of a possible aluminium concentration, the following organs were investigated : kidney, liver, gill and digestive tractus, using both microanalytical techniques described above.In the kidney ion images showed aluminium emission from tubule lysosomes with a ring-shaped localization along the apical border of the epithetial cells; aluminium emissions from the tubule lumen and from the pigment granules of the melanocytes were also observed. Using the electron microprobe, X-ray emission spectra of aluminium associated with phosphorus were obtained from lysosomes and pigment granules. In the liver and in the gills, ion images showed a high aluminium emission from the same organelles and X-ray spectra of aluminium and phosphorus were also obtained. Moreover, in the pyloric caeca, large extracellular deposits of aluminium were detected : they measured about 100 µm in length and were located in places where tissues had been destroyed.The same structural, ultrastructural and microanalytical investigations were performed on the control trouts from which non aluminium detection was obtained.In conclusion, two processes appear to be involved in the aluminium accumulation in the brown trout. The first one corresponds to a well known insolubilisation of aluminium phosphate inside the lysosomes, due to an acidic phosphatase enzymatic activity; aluminium is also trapped inside pigment granules. Both of these mechanisms of storage inside membrane-limited organelles, prevent cells from any interior damage. The second one corresponds to the formation of large extracellular deposits which are likely to provoke injuries leading to the tissue destruction. Such data demonstrating basic mechanisms of aluminium accumulation in a fish, could not have been obtained using total analytical methods

De minha vida: Poesia e verdade – sobre a literariedade da autobiografia de Goethe

The article discusses the relevance of Johann Wolfgang Goethe’s autobiography to the literary canon and to the genre of writings about one’s self, analyzing its composition on the basis of the poet’s ideas on morphology and questioning more recent approaches that include the book in the realm of (self)fiction. The discussion is guided by the concept of literariness and its constitutive aspects, poeticism and fictionality.O presente artigo discute a relevância da autobiografia de Johann Wolfgang Goethe no cânone da literatura e da escrita do eu, analisando sua composição baseada nas ideias morfológicas do poeta e questionando abordagens mais recentes que aproximam o livro da (auto-)ficção. A discussão é norteada pelo conceito da literariedade e seus aspectos constitutivos, a poeticidade e a ficcionalidade

Monitoring weeder robots and anticipating their functioning by using advanced topological data analysis

The present paper aims at analyzing the topological content of the complex trajectories that weeder-autonomous robots follow in operation. We will prove that the topological descriptors of these trajectories are affected by the robot environment as well as by the robot state, with respect to maintenance operations. Most of existing methodologies enabling efficient diagnosis are based on the data analysis, and in particular on some statistical quantities derived from the data. The present work explores the use of an original approach that instead of analyzing quantities derived from the data, analyzes the “shape” of the data, that is, the time series topology based on the homology persistence. We will prove that this procedure is able to extract valuable patterns able to discriminate the trajectories that the robot follows depending on the particular patch in which it operates, as well as to differentiate the robot behavior before and after undergoing a maintenance operation. Even if it is a preliminary work, and it does not pretend to compare its performances with respect to other existing technologies, this work opens new perspectives in considering quite natural and simple descriptors based on the intrinsic information that data contains, with the aim of performing efficient diagnosis and prognosis. Copyright © 2021 Frahi, Sancarlos, Galle, Beaulieu, Chambard, Falco, Cueto and Chinesta

Effects of Proton Center Closure on Pediatric Case Volume and Resident Education at an Academic Cancer Center

Purpose To analyze effects of closure of an academic proton treatment center (PTC) on pediatric case volume, distribution, and resident education. Methods and Materials This was a review of 412 consecutive pediatric (age ≤18 years) cases treated at a single institution from 2012 to 2016. Residents' Accreditation Council for Graduate Medical Education case logs for the same years were also analyzed. Characteristics of the patient population and resident case volumes before and after closure of the PTC are reported. Results Overall pediatric new starts declined by approximately 50%, from 35 to 70 per 6 months in 2012 to 2014 to 22 to 30 per 6 months in 2015 to 2016. Central nervous system (CNS) case volume declined sharply, from 121 patients treated in 2012 to 2015 to 18 patients in 2015 to 2016. In 2012 to 2014 our institution treated 36, 24, and 17 patients for medulloblastoma/intracranial primitive neuroectodermal tumor, ependymoma, and low-grade glioma, respectively, compared with 0, 1, and 1 patient(s) in 2015 to 2016. Forty-nine patients were treated with craniospinal radiation (CSI) from 2012 to 2014, whereas only 2 patients underwent CSI between 2015 and 2016. Hematologic malignancy patient volume and use of total body irradiation remained relatively stable. Patients treated when the PTC was open were significantly younger (9.1 vs 10.7 years, P=.010) and their radiation courses were longer (35.4 vs 20.9 days, P<.0001) than those treated after its closure. Resident case logs showed only a small decline in total pediatric cases, because the percentage of pediatric cases covered by residents increased after PTC closure; however, residents logged fewer CNS cases after PTC closure versus before. Conclusions Overall pediatric case volume decreased after PTC closure, as did the number of patients treated for potentially curable CNS tumors. Our findings raise important questions regarding resident training in pediatric radiation oncology as these cases become increasingly concentrated at specialized centers