Dutch Dike Breach, Wilnis 2003

In August 2003, after a very dry and warm summer, one of the dikes along a canal in The Netherlands failed at night. Because of this dike breach, the water in the canal started to run into a housing quarter of the village Wilnis, which is about 30 km Southeast of Amsterdam. A local contractor immediately started to close off the canal. By the time this was finished, 600 houses were already half a meter under water. The 2000 residents were evacuated in the early morning. Almost all residents could return to their homes the same evening after the water was pumped out of this area. Like many other small dikes in The Netherlands, the complete dike consists of peat. Since peat has a relatively low specific weight, a peat dike has a higher risk of being pushed aside by water pressure than sand or clay dikes. This horizontal sliding is a rare type of failure mechanism. Though, when the stability of this dike is checked with a simple one page computation, it becomes clear that the failure of the dike after a dry period was a realistic threat. For many years it was known that this part of dike was at risk. This was reported to the minister of Public Works in 1993, but the two involved provincial authorities, the provincial government and the water board, did not take steps until after the dike failure

The Stability of Flood Defenses on Permeable Soils: The London Avenue Canal Failures in New Orleans

The two failures of the London Avenue Canal floodwalls contributed largely to the flooding of central New Orleans due to hurricane Katrina. In this paper, both failures are analyzed and compared to each other since the flood defenses are both located on permeable soils. Photo’s observation and calculations are used for the analysis. Both failures are caused by the permeable sand layer below the floodwall that allowed high pore water pressures to develop below the floodwall. However, the south breach seems to be caused by the piping failure mechanism and the north breach by loss of stability. At the South breach, the impermeable top layer was thicker than at the North breach, increasing the stability. The North beach was less vulnerable for piping and the lack of stability caused a large breach. The London Avenue Canal failures are a clear yet tragic example of the failure of flood defenses on permeable soils. The failures show that multiple failure mechanism may occur and since there are many flood defenses on permeable soils world wide, the lessons from Katrina can be used to prevent future catastrophes

Effects of self-assessment feedback on self-assessment and task-selection accuracy

Effective self-regulated learning in settings in which students can decide what tasks to work on, requires accurate self-assessment (i.e., a judgment of own level of performance) as well as accurate task selection (i.e., choosing a subsequent task that fits the current level of performance). Because self-assessment accuracy is often low, task-selection accuracy suffers as well and, consequently, self-regulated learning can lead to suboptimal learning outcomes. Recent studies have shown that a training with video modeling examples enhanced self-assessment accuracy on problem-solving tasks, but the training was not equally effective for every student and, overall, there was room for further improvement in self-assessment accuracy. Therefore, we investigated whether training with video examples followed by feedback focused on selfassessment accuracy would improve subsequent self-assessment and task-selection accuracy in the absence of the feedback. Experiment 1 showed, contrary to our hypothesis, that selfassessment feedback led to less accurate future self-assessments. In Experiment 2, we provided students with feedback focused on self-assessment accuracy plus information on the correct answers, or feedback focused on self-assessment accuracy, plus the correct answers and the opportunity to contrast those with their own answers. Again, however, we found no beneficial effect of feedback on subsequent self-assessment accuracy. In sum, we found no evidence that feedback on self-assessment accuracy improves subsequent accuracy. Therefore, future research should address other ways improving accuracy, for instance by taking into account the cues upon which students base their self-assessments

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The politics and administration of institutional chang

Нове видання з історії становлення кодикографії та бібліографії стародруків України

Розглядається монографічне видання, яке вперше комплексно представ-ляє загальний стан колекційних рукописних та книжкових фондів бібліотек і музеїв в Україні в другій половині ХІХ – 30-х роках ХХ ст.; формування та діяльність наукових центрів з вивчення історії книги в Україні у період, коли археографічна діяльність досягла найвищого рівня свого розвитку.Рассматривается монографическое издание, которое впервые комплексно представляет общее состояние коллекционных рукописных и книжных фондов библиотек и музеев в Украине во второй половине ХіХ – 30-х годах ХХ ст.; формирование и деятельность научных центров по изучению истории книги в Украине в период, когда археографическая деятельность достигла наивысшего уровня своего развития.The consideration of the monographic edition which for the firs time represents in complex the general condition of collection hand-written and book funds of libraries and museums in Ukraine in the second half of ХIХ–30-th years of ХХ century, the formation and activity of scientific centres on studying book history in Ukraine at the period of the highest level of the archaeographic activity development

Training self‐assessment and task‐selection skills to foster self‐regulated learning: Do trained skills transfer across domains?

Students' ability to accurately self‐assess their performance and select a suitable subsequent learning task in response is imperative for effective self‐regulated learning. Video modeling examples have proven effective for training self‐assessment and task‐selection skills, and—importantly —such training fostered self‐regulated learning outcomes. It is unclear, however, whether trained skills would transfer across domains. We investigated whether skills acquired from training with either a specific, algorithmic task‐selection rule or a more general heuristic task‐selection rule in biology would transfer to self‐regulated learning in math. A manipulation check performed after the training confirmed that both algorithmic and heuristic training improved task‐selection skills on the biology problems compared with the control condition. However, we found no evidence that students subsequently applied the acquired skills during self‐regulated learning in math. Future research should investigate how to support transfer of task‐selection skills across domains

Effects of self-assessment feedback on self-assessment and task-selection accuracy

Effective self-regulated learning in settings in which students can decide what tasks to work on, requires accurate self-assessment (i.e., a judgment of own level of performance) as well as accurate task selection (i.e., choosing a subsequent task that fits the current level of performance). Because self-assessment accuracy is often low, task-selection accuracy suffers as well and, consequently, self-regulated learning can lead to suboptimal learning outcomes. Recent studies have shown that a training with video modeling examples enhanced self-assessment accuracy on problem-solving tasks, but the training was not equally effective for every student and, overall, there was room for further improvement in self-assessment accuracy. Therefore, we investigated whether training with video examples followed by feedback focused on selfassessment accuracy would improve subsequent self-assessment and task-selection accuracy in the absence of the feedback. Experiment 1 showed, contrary to our hypothesis, that selfassessment feedback led to less accurate future self-assessments. In Experiment 2, we provided students with feedback focused on self-assessment accuracy plus information on the correct answers, or feedback focused on self-assessment accuracy, plus the correct answers and the opportunity to contrast those with their own answers. Again, however, we found no beneficial effect of feedback on subsequent self-assessment accuracy. In sum, we found no evidence that feedback on self-assessment accuracy improves subsequent accuracy. Therefore, future research should address other ways improving accuracy, for instance by taking into account the cues upon which students base their self-assessment

Discovery of Radio Outbursts in the Active Nucleus of M81

The low-luminosity active galactic nucleus of M81 has been monitored at centimeter wavelengths since early 1993 as a by-product of radio programs to study the radio emission from Supernova 1993J. The extensive data sets reveal that the nucleus experienced several radio outbursts during the monitoring period. At 2 and 3.6 cm, the main outburst occurred roughly in the beginning of 1993 September and lasted for approximately three months; at longer wavelengths, the maximum flux density decreases, and the onset of the burst is delayed. These characteristics qualitatively resemble the standard model for adiabatically expanding radio sources, although certain discrepancies between the observations and the theoretical predictions suggest that the model is too simplistic. In addition to the large-amplitude, prolonged variations, we also detected milder changes in the flux density at 3.6 cm and possibly at 6 cm on short (less than 1 day) timescales. We discuss a possible association between the radio activity and an optical flare observed during the period that the nucleus was monitored at radio wavelengths.Comment: To appear in The Astronomical Journal. Latex, 18 pages including embedded figures and table