Investigación sobre las ideas de los estudiantes acerca de la Historia

Los educadores deberían sentirse alentados por la consistencia con que la investigación muestra que la juventud participa activamente en el proceso de construcción de significado a partir de sus encuentros con la historia. También deberían sentirse satisfechos de saber que la docencia formal puede tener impacto en el desarrollo de las ideas de los estudiantes. Por otro lado, la investigación demuestra que algunos aspectos del sujeto pueden ser problemáticos: algunos estudiantes pueden tener problemas para reconciliar la historia escolar con las narraciones que han aprendido fuera de la escuela, por ejemplo, y no desarrollan fácilmente comprensiones completas del uso de la evidencia o del impacto de los factores sociales en las acciones y perspectivas de la gente del pasado. La investigación más importante en el futuro, por tanto, debería incluir la identificación de la diversidad de ideas que los estudiantes de orígenes diferentes aportan a la clase, y debería explorar el efecto de las prácticas docentes específicas en la comprensión. Este trabajo no sólo contribuiría a la producción académica sobre las ideas de los estudiantes acerca de la historia, sino que también podría conducir a aplicaciones prácticas en el aula.Educators should be encouraged by the consistency with which research shows that young people actively participate in the process of constructing meaning from their encounters with history. They should also be pleased to know that formal instruction can have an impact on students’ developing ideas. Besides, research proves that some aspects of the subject can be problematic: some students may experience some difficulty in reconciling school History with the narratives they have learnt outside school, for example. Hence, they do not easily develop complete understandings of the use of evidence or the impact of societal factors on the actions and perspectives of people in the past. The most important research in the future, therefore, would involve identifying the diversity of ideas that students from different backgrounds bring to the classroom and exploring the effect of specific instructional practices on their understanding. Such work would not only contribute to academic scholarship on students’ ideas about history but might also lead to practical classroom applications

Is what you see what you get? representations, metaphors and tools in mathematics didactics

This paper is exploratory in character. The aim is to investigate ways in which it is possible to use the theoretical concepts of representations, tools and metaphors to try to understand what learners of mathematics ‘see’ during classroom interactions (in their widest sense) and what they might get from such interactions. Through an analysis of a brief classroom episode, the suggestion is made that what learners see may not be the same as what they get. From each of several theoretical perspectives utilised in this paper, what learners ‘get’ appears to be something extra. According to our analysis, this something ‘extra’ is likely to depend on the form of technology being used and the representations and metaphors that are available to both teacher and learner

Study of pyridine-mediated electrochemical reduction of CO2 to methanol at high CO2 pressure

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The recently proposed highly efficient route of pyridine-catalyzed CO 2 reduction to methanol was explored on platinum electrodes at high CO 2 pressure. At 55 bar (5.5 MPa) of CO 2 , the bulk electrolysis in both potentiostatic and galvanostatic regimes resulted in methanol production with Faradaic yields of up to 10 % for the first 5–10 C cm −2 of charge passed. For longer electrolysis, the methanol concentration failed to increase proportionally and was limited to sub-ppm levels irrespective of biasing conditions and pyridine concentration. This limitation cannot be removed by electrode reactivation and/or pre-electrolysis and appears to be an inherent feature of the reduction process. In agreement with bulk electrolysis findings, the CV analysis supported by simulation indicated that hydrogen evolution is still the dominant electrode reaction in pyridine-containing electrolyte solution, even with an excess CO 2 concentration in the solution. No prominent contribution from either a direct or coupled CO 2 reduction was found. The results obtained suggest that the reduction of CO 2 to methanol is a transient process that is largely decoupled from the electrode charge transfer

Leveraging information technology to enable network centric engineer reconnaissance operations

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.Vita.Includes bibliographical references (p. 89-91).The Naval Construction Force has traditionally depended on outside sources to obtain and analyze engineering data in contingency situations. The Navy has embarked on an initiative to develop Seabee Engineer Reconnaissance Teams to perform this function, both as a basis for projects slated for in-house construction and as a product to deliver to other organizations. Exercises and operations have thus far shown that the concept is viable, but Seabee Engineer Reconnaissance Teams have encountered problems with data gathering and reporting, and transmission of data and images. Concurrently, the Department of Defense is pursuing a transformation toward network-centric warfare. Network Centric Warfare represents a powerful set of warfighting concepts and associated military capabilities that allow warfighters to take full advantage of all available information in order to bring all available assets to bear in a rapid and flexible manner. This research explores the state of the practice of military engineer reconnaissance as described by established Army doctrine and as enacted by Navy Seabee Engineer Reconnaissance Teams. Commercial information technology applications are reviewed in the areas of geographic information systems, collaborative design, and wireless communications. Solutions are proposed for their potential to enable network centric engineer reconnaissance operations. Network Centric Warfare concepts provide a framework for analyzing the state of the practice in military engineer reconnaissance versus the state of the art in information technology. Current status is assessed and a methodology is proposed to move the Navy quickly forward on the continuum of the Network Centric Operations Maturity Model that enables shared situational awareness, with a brief discussion on the implications for decentralized decision-making.by Keith W. Barton.S.M

The crystal structures of diaquatetra (β-picoline)M(II) perchlorate, [M(H20)2(C6H7N)4](ClO4)2(M=CU,CO)

【Abstract】Crystals of the Cu(II), Co(II), and Ni(II) β-picoline complexes ([M(H2O)2(C6H7N)4](ClO4)2, M = Cu, Co, Ni) all showed monoclinic rhombohedral morphology and were shown by diffraction methods to be isomorphous. The structures of the Cu(II) and Co(II) complexes have been determined in detail. ＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ ￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣ Atom a(A) b(A) c(A) β(leg) Dm Dx Colour ￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣ Cu(Ⅱ) 15.292(4) 9.672(2) 20.579(5) 94.73(2) 1.45(1) 1.467 Bluc Co(Ⅱ) 15.878(12) 9.374(3) 20.661(7) 96.50(4) 1.45(1) 1.448 Pink Ni(Ⅱ) 15.7 9.3 20.4 96.5 1.44(1) Palc bluc ￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣ The space group of crystals of the three complexes is C2/c. The structures were solved by the Patterson method. The structures of the Cu(II) and Co(II) complex were refined to a final Rw (on |F|) of 0.050 and 0.068 for 1918 and 2455 independent reflections, respectively, as measured with a modified Picker diffractometer. The structure of these complexes consists of coordination polyhedra with formulation [M(H2O)2(β-picoline)4]2+ and perchlorate counterions. The ions are connected by hydrogen bonds of average length 2.76 Å in the Co(II) complex and 2.82 Å in the Cu(II) complex. The four N atoms of the β-picoline ligands form an equatorial plane with average [M—N] distances of 2.17 Å in the Co(II) complex and 2.03 Å in the Cu(II) complex. The water ligands are in apical positions with [M—O] distances of 2.124(6) Å and 2.493(10) Å in the Co(II) and Cu(II) complexes respectively. This large difference in bond lengths is manifested in marked differences in the appearance of crystals of the two compounds and is consistent with an expected Jahn–Teller effect. The thermal factors suggest that the perchlorate ion undergoes enhanced librational motion

Difference in glaucoma progression between the first and second eye after consecutive bilateral glaucoma surgery in patients with bilateral uveitic glaucoma

PURPOSE: To determine whether the second eyes (SE) of patients with bilateral uveitic glaucoma undergoing filtration surgery have more glaucomatous progression in terms of visual acuity, visual field (VF) and optic nerve changes compared to the first eyes (FE). METHODS: This retrospective study analysed data of 60 eyes from 30 patients with bilateral uveitic glaucoma who had undergone glaucoma surgery in both eyes on separate occasions. Humphrey VF progression was assessed using the Progressor software. RESULTS: The pre-operative IOP between the FE (43.1 ± 7.7 mmHg) and SE (40 ± 8.7 mmHg) was not statistically significant (p = 0.15). IOP reduction was greater in the FE (64 %) than SE (59.7 %) post-operatively, but the mean IOP at the final visit in the FE (12.3 ± 3.9 mmHg) and SE (14.5 ± 7 mmHg) was not statistically different (p = 0.2). There was no significant change in mean logMAR readings pre and post-operatively (0.45 ± 0.6 vs 0.37 ± 0.6, p = 0.4) or between the FE and SE. The number of SE with CDR > 0.7 increased by 23 % compared to the FE. From 23 available VFs, five SE (21.7 %) progressed at a median of five locations (range 1-11 points) with a mean local slope reduction of 1.74 ± 0.45 dB/year (range -2.39 to -1.26), whereas only one FE progressed. However, there was no significant difference between mean global rate of progression between the FE (-0.9 ± 1.6 dB/year) and SE (-0.76 ± 2.1 dB/year, p = 0.17) in the Humphrey VF. CONCLUSION: In eyes with bilateral uveitic glaucoma requiring glaucoma surgery, the SEs had more progressed points on VF and glaucomatous disc progression compared to FEs at the final visit

DNA methylation at birth within the promoter of ANRIL predicts markers of cardiovascular risk at 9 years

Aims: Antisense non-coding RNA in the INK4 locus (ANRIL) fixed genetic variants have consistently been linked with coronary heart disease (CHD) risk. We investigated relationships between perinatal ANRIL promoter DNA methylation and CHD risk markers in children aged 9 years. Genetic variants in the non-coding RNA ANRIL identify it as an important CHD risk locus. Increasing evidence suggests that the early life environment may act through epigenetic processes to influence later CHD risk markers such as increased arterial pulse wave velocity (PWV, a measure of arterial stiffness) blood pressure or heart rate.Methods and results: Using pyrosequencing, ANRIL DNA methylation at nine CpG sites was measured in the umbilical cord from 144 children in a UK mother-offspring cohort and related to the descending aorta PWV measured by velocity-encoded phase contrast MRI at age 9 years. Perinatal methylation was not associated with child’s later blood pressure, but higher methylation at CpG5 was associated with increased childhood PWV (??=?0.066 m/s/10 % methylation increase [95 % CI, 0.004 to 0.128], p?=?0.037); 10 % decreases in methylation at CpG1 and CpG2 were associated with increased heart rate (CpG1 ??=?1.93 [0.07 to 3.8] beats/min, p?=?0.041; CpG2 ??=?2.30 [0.18 to 4.41] beats/min, p?=?0.033, accounting for potential confounding variables). The associations with perinatal ANRIL promoter methylation were independent of neighbouring fixed genetic variants.Conclusions: Our findings suggest developmental epigenetic regulation of ANRIL promoter methylation as a factor in later CHD risk in children.<br/