Peer effects, motivation, and learning

Abstract: This paper confirms the existence of peer effects in a learning process with data from an experiment. The experimental setting offers an insight into the mechanisms of peer interaction and provides complementary information to empirical studies using survey or administrative data. The results show that a partner has a motivational effect even before the actual cooperation takes place. The evidence for optimal group composition is not robust. Some of the "better" students improve the performance of their partner but they induce lower motivation

Major Advance of South Georgia Glaciers during the Antarctic Cold Reversal Following Extensive Sub-Antarctic Glaciation

The history of glaciations on Southern Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-Antarctic South Georgia in particular. Here, using sea-floor geophysical data and marine sediment cores, we resolve the record of glaciation offshore of South Georgia through the transition from the Last Glacial Maximum to Holocene. We show a sea-bed landform imprint of a shelf-wide last glacial advance and progressive deglaciation. Renewed glacier resurgence in the fjords between c. 15,170 and 13,340 yr ago coincided with a period of cooler, wetter climate known as the Antarctic Cold Reversal, revealing a cryospheric response to an Antarctic climate pattern extending into the Atlantic sector of the Southern Ocean. We conclude that the last glaciation of South Georgia was extensive, and the sensitivity of its glaciers to climate variability during the last termination more significant than implied by previous studies. The glaciated history of South Georgia is debated, with many suggesting a coastal limit to the island’s ice cap during the last glaciation. Here, the authors show extensive ice-cap cover of the continental block during this time and a readvance of glaciers to fjord mouths during the Antarctic Cold Reversal

Medição de tempo de atravessamento e inventário em processo em manufatura controlada por ordens de fabricação Lead-time and work-in-process measurement in manufacture controlled by manufacturing orders

Este artigo trata da aplicação de um método para medição do tempo de atravessamento e do inventário em processo em operações de manufatura controladas por ordens de fabricação. Revisam-se os conceitos de tempo de atravessamento, inventário e filas em manufatura e apresenta-se o método proposto. Coletaram-se as datas de início e término e as quantidades fabricadas em cem ordens de fabricação de um fabricante de máquinas. O método foi aplicado e os resultados permitiram análises sobre a gestão do prazo e da confiabilidade de entrega e da fila na manufatura. Tais critérios podem ser importantes quando a competição no negócio também considera a rapidez e a confiabilidade nas entregas.<br>This paper presents an application of a method for measuring lead-time and work-in-process in manufacturing operations controlled by orders. We review the concepts of lead-time, inventory and queues in manufacturing and present the proposed method. We began by collecting data from one hundred orders, which include release and completion time and delivered quantities. The method was applied and allowed a discussion involving time-to-deliver, dependability of orders and management of queues in shop-floor, which can be important in business competition, when customers expect, from manufacturer, quick response and on-time delivers

Tissue-resident macrophages self-maintain locally throughout adult life with minimal contribution from circulating monocytes

Despite accumulating evidence suggesting local self-maintenance of tissue macrophages in the steady state, the dogma remains that tissue macrophages derive from monocytes. Using parabiosis and fate-mapping approaches, we confirmed that monocytes do not show significant contribution to tissue macrophages in the steady state. Similarly, we found that after depletion of lung macrophages, the majority of repopulation occurred by stochastic cellular proliferation in situ in a macrophage colony-stimulating factor (M-Csf)- and granulocyte macrophage (GM)-CSF-dependent manner but independently of interleukin-4. We also found that after bone marrow transplantation, host macrophages retained the capacity to expand when the development of donor macrophages was compromised. Expansion of host macrophages was functional and prevented the development of alveolar proteinosis in mice transplanted with GM-Csf-receptor-deficient progenitors. Collectively, these results indicate that tissue-resident macrophages and circulating monocytes should be classified as mononuclear phagocyte lineages that are independently maintained in the steady state